CommercialToolry

An In-Depth Guide to Customize Running Shoes: Standards, Grades, and Performance

Types of Customizable Running Shoes

Running shoes are not one-size-fits-all—especially when it comes to customization. Modern athletic footwear offers a wide range of specialized designs tailored to different foot types, running styles, and terrains. Choosing the right type of customizable running shoe can significantly enhance comfort, performance, and injury prevention during long-distance jogging, training, or trail adventures. Below is a detailed breakdown of the primary types of running shoes available for personalization, including key features, benefits, and ideal use cases.

Stability Shoes

Designed for runners who experience overpronation—where the foot rolls inward excessively during the gait cycle—stability shoes offer reinforced medial (inner) support to correct alignment and reduce strain on joints.

Advantages
  • Corrects overpronation for improved biomechanics
  • Enhanced arch support for medium to high arches
  • Reduces risk of knee, shin, and ankle injuries
  • Smooth heel-to-toe transition
Limitations
  • May feel restrictive for neutral runners
  • Slightly heavier than neutral shoes
  • Less flexible in the midfoot

Best for: Runners with mild to moderate overpronation, daily training, road running, and long-distance jogging

Customization Options: Personalized insoles with variable arch support, breathable mesh uppers, color-matched accents, and custom midsole density for targeted cushioning.

Cushioning (Neutral) Shoes

Also known as neutral cushioned shoes, these are ideal for runners with a natural gait and no significant pronation issues. They prioritize shock absorption and soft landings, making them perfect for high-mileage runners.

Advantages
  • Superior impact protection on hard surfaces
  • Soft, plush feel underfoot
  • Ideal for long-distance running and marathon training
  • Lightweight and flexible design
Limitations
  • Limited support for overpronators
  • May wear out faster due to softer materials
  • Less responsive for speed workouts

Best for: Neutral runners, long road runs, treadmill workouts, and individuals seeking maximum comfort

Customization Options: Gel or air-based cushioning inserts, personalized heel counters, custom upper materials (e.g., cooling mesh or moisture-wicking fabric), and aesthetic personalization like name embroidery or color blocking.

Motion Control Shoes

Built for severe overpronators or runners with flat feet, motion control shoes feature rigid heel counters, wide bases, and firm midsoles to limit excessive foot movement and provide maximum support.

Advantages
  • Exceptional support for flat feet and low arches
  • Durable construction for long-term use
  • Reduces inward rolling dramatically
  • Stable platform for heavy runners or those with joint concerns
Limitations
  • Heavier and less flexible than other types
  • May feel stiff during initial break-in period
  • Not suitable for neutral or supinated runners

Best for: Runners with flat feet, severe overpronation, or those recovering from lower-body injuries

Customization Options: Specialized orthotic-compatible insoles, reinforced heel cups, durable outsole materials, and breathable yet supportive uppers for all-day comfort.

Trail Running Shoes

Engineered for off-road terrain, trail running shoes feature aggressive lug soles, rock plates, reinforced toe caps, and water-resistant uppers to handle mud, gravel, roots, and wet conditions safely.

Advantages
  • Superior grip on loose or uneven surfaces
  • Protects feet from rocks, roots, and debris
  • Enhanced durability in rugged environments
  • Often includes water-resistant or quick-drying materials
Limitations
  • Not ideal for road running due to stiff soles
  • Can be heavier than road shoes
  • May require more break-in time

Best for: Off-road runners, hiking trails, mountainous terrain, and adventure racing

Customization Options: Custom-fit insoles for rocky terrain, abrasion-resistant overlays, reflective details for low-light visibility, and personalized color schemes that reflect outdoor aesthetics.

Shoe Type Primary Benefit Foot Type Customization Focus Ideal For
Stability Shoes Support for mild overpronation Medium to high arches Arch support, breathable uppers Road running, daily training
Cushioning Shoes Maximum shock absorption Neutral gait, normal arches Gel/air inserts, soft midsoles Long-distance running, marathons
Motion Control Shoes Maximum support for flat feet Low arches, severe overpronation Orthotic insoles, rigid heel counters Heavy runners, injury prevention
Trail Running Shoes Traction and protection off-road All foot types (terrain-dependent) Durable materials, grip optimization Trails, mountains, muddy paths

Expert Tip: When customizing running shoes, always consider your gait analysis and foot shape. A professional fitting or 3D foot scan can help determine the optimal support, cushioning, and fit for your personalized footwear, ensuring both comfort and performance over time.

Design of Customizable Running Shoes

Customizable running shoes go beyond standard technical specifications by integrating user-centric design elements that enhance both performance and personal expression. These shoes are engineered not only for comfort and functionality but also to reflect individual style, lifestyle needs, and even technological preferences. The customization process considers multiple design dimensions—material selection, personal branding, and smart technology integration—to deliver a truly unique and optimized footwear experience.

Key Design Factors in Customizable Running Shoes

Color and Material Choices

One of the most influential aspects of customizable running shoes is the selection of colors and materials, which directly impacts both aesthetics and performance. Customers can tailor their shoes to match personal style or performance requirements, choosing from a wide array of fabrics and finishes.

For runners prioritizing breathability and lightweight comfort, advanced mesh uppers and moisture-wicking synthetic textiles are popular choices. These materials promote airflow, reduce heat buildup, and help maintain foot dryness during intense workouts.

On the other hand, those seeking durability or eco-conscious options may opt for reinforced synthetic leather, recycled polyester, or bio-based materials derived from algae and ocean plastics. These sustainable alternatives not only reduce environmental impact but also offer enhanced abrasion resistance and structural support.

The visual design of the upper—including color blocking, gradient effects, and texture layering—allows for creative expression while maintaining ergonomic integrity. Designers often use 3D modeling tools to preview material combinations, ensuring both visual appeal and functional synergy.

Branding and Personalization

Custom branding and personalization transform running shoes from athletic gear into personal statements. Whether for individual use or group identity, this feature enables users to imprint logos, names, motivational quotes, or custom graphics directly onto the shoe.

Advanced digital printing and embroidery techniques allow for high-resolution, fade-resistant designs that withstand regular wear and washing. Some platforms even offer augmented reality (AR) previews, letting customers visualize their personalized designs in real-time before production.

This level of customization is especially valuable for sports teams, corporate events, charity runs, and fitness clubs. It fosters a sense of unity and team spirit while still allowing members to express individuality through color schemes or personal touches.

Additionally, limited-edition custom runs or commemorative designs (e.g., marathon milestones or personal achievements) add emotional value, turning shoes into keepsakes. Brands leverage this to strengthen customer loyalty and engagement through co-creation experiences.

Technology Integration

Modern customizable running shoes increasingly incorporate smart technology to elevate performance tracking and user interaction. Embedded sensors can monitor key metrics such as stride length, cadence, ground contact time, distance traveled, and even foot strike patterns.

These sensors sync wirelessly with mobile applications via Bluetooth or NFC, providing real-time feedback and long-term analytics to help runners improve form, prevent injury, and optimize training routines. Some systems also offer GPS integration and heart rate monitoring when paired with wearables.

Future-forward designs are exploring energy-harvesting soles that convert kinetic energy into power for sensors, reducing reliance on external charging. Others include adaptive cushioning systems that adjust firmness based on terrain or running speed using microfluidic chambers or AI-driven algorithms.

Beyond performance, technology enhances sustainability—smart tags embedded in the shoe can track lifecycle data, enabling easier recycling or resale verification. As wearable tech evolves, customizable running shoes are becoming intelligent companions in fitness journeys, blending fashion, function, and innovation seamlessly.

Ergonomics & Fit Customization

While not explicitly mentioned in the original content, fit personalization is a critical component of modern shoe design. Advanced customization platforms now offer options for adjusting insole thickness, arch support height, heel counter rigidity, and even toe box width to accommodate different foot shapes and biomechanics.

Some brands use foot scanning technology—via smartphone apps or in-store kiosks—to generate 3D foot models, ensuring a precise fit. This data-driven approach minimizes discomfort, reduces blisters, and lowers the risk of long-term injuries like plantar fasciitis or shin splints.

Custom midsole density and cushioning zones can be tailored to running style (e.g., neutral, overpronation, supination), making each pair uniquely suited to the wearer’s gait. Combined with material and aesthetic choices, this holistic approach ensures that every aspect of the shoe supports both performance and personal preference.

Design Element Functional Benefit Personalization Option
Mesh & Breathable Fabrics Improved airflow, reduced sweat accumulation Color, weave pattern, ventilation zones
Recycled & Sustainable Materials Lower environmental impact, durable construction Material source (e.g., ocean plastic, cork), finish type
Smart Sensors & Connectivity Performance tracking, injury prevention Data display preferences, app integration
Custom Branding & Graphics Team identity, personal expression Logos, text, images, AR previews
Ergonomic Fit Adjustments Enhanced comfort, injury reduction Arch support, cushioning firmness, width

Trends Shaping the Future of Custom Running Shoes

  • Sustainable Innovation: Brands are investing in biodegradable foams, plant-based dyes, and closed-loop recycling programs to minimize ecological footprint without compromising performance.
  • AI-Powered Design: Artificial intelligence analyzes user data to recommend optimal material combinations, color schemes, and structural features based on activity type and climate.
  • On-Demand Manufacturing: 3D printing and automated cutting reduce waste and enable localized production, shortening delivery times and supporting circular economy models.
  • Wearable Integration: Shoes are becoming part of a broader health ecosystem, syncing with smartwatches, fitness apps, and even smart clothing for holistic wellness monitoring.
  • Community-Driven Design: Crowdsourcing platforms allow users to vote on or contribute to new designs, fostering deeper brand engagement and innovation.
  • Important: While customization offers immense flexibility, it's essential to balance aesthetic desires with biomechanical needs. Over-prioritizing style over support or using non-breathable materials in hot climates can lead to discomfort or injury. Always consider your running environment, foot type, and performance goals when designing your ideal shoe. Consult with a podiatrist or footwear specialist if you have specific medical or structural concerns.

    How to Choose and Customize Running Shoes

    Selecting the right running shoes—especially customized ones—is a crucial step in enhancing performance, preventing injuries, and ensuring long-term comfort. Unlike off-the-shelf models, custom running shoes are tailored to your unique biomechanics, foot structure, and running goals. To make the best choice, consider several key factors that influence fit, function, and overall effectiveness.

    Understand Your Running Style and Gait Analysis

    Your running gait—the way your foot strikes the ground and rolls during each stride—is fundamental to choosing the right shoe support. Runners typically fall into three main categories: neutral, overpronators (feet roll inward excessively), or underpronators/supinators (feet roll outward). Identifying your gait pattern ensures your customized shoes provide the correct stability, cushioning, and alignment correction.

    • Visit specialty running stores or sports clinics that offer video gait analysis using treadmills and slow-motion playback
    • Look for signs of wear on existing shoes—excessive inner sole wear often indicates overpronation
    • Custom orthotics or insoles can be integrated into your shoes to correct imbalances and improve efficiency
    • Runners with flat feet usually benefit from motion control features, while high arches may need extra cushioning

    Key insight: A proper gait analysis can reduce injury risk by up to 50% by aligning footwear with natural movement patterns.

    Accurately Measure Your Feet

    Many people wear shoes that don’t truly fit because they assume their size hasn’t changed—or never get professionally measured. Feet can change over time due to age, weight fluctuations, or activity level. For custom shoes, precise measurements are non-negotiable.

    • Measure both feet at the end of the day when they’re slightly swollen, as this reflects real running conditions
    • Capture length, width, arch height, instep circumference, and toe box dimensions
    • Account for volume differences—some feet are narrow but high-arched, requiring specific upper designs
    • Use 3D scanning technology if available, which provides millimeter-level accuracy for full foot mapping

    Pro tip: Always size based on your larger foot to prevent blisters, numbness, or toe jamming during long runs.

    Select the Right Customization Options

    Modern customization goes far beyond color choices. Today’s advanced running shoes allow personalization of structural and functional components to match individual biomechanics and preferences.

    • Insoles and Orthotics: Custom-molded insoles provide targeted arch support, correcting overpronation or accommodating flat/high arches
    • Midsole Materials: Choose between EVA foam (lightweight cushioning), polyurethane (durability), or newer compounds like Pebax or Boost for energy return
    • Upper Design: Opt for breathable mesh for hot climates, reinforced uppers for stability, or seamless knits for a sock-like fit
    • Width and Fit Profiles: Many brands offer wide, narrow, or extra-depth options to prevent pressure points
    • Heel Counter & Collar Padding: Adjustable stiffness and cushioning improve heel lock and reduce Achilles irritation

    Smart customization: Combine a responsive midsole with a semi-rigid arch support for marathon training, or prioritize lightweight breathability for speed workouts.

    Consult with Footwear Professionals

    While online tools and DIY assessments exist, nothing replaces expert guidance when investing in custom footwear. Certified pedorthists, podiatrists, or trained fitters bring experience and diagnostic tools to ensure your shoes meet both functional and medical needs.

    • Work with specialists who use dynamic pressure mapping to identify high-stress zones on your foot
    • Seek professionals affiliated with reputable running labs or sports medicine centers
    • Ask about integration with physical therapy plans if recovering from injuries like plantar fasciitis or shin splints
    • Get recommendations based on your running terrain—trail, road, track—or racing goals

    Expert advantage: A professional can recommend subtle modifications—like slight heel lifts or lateral wedges—that significantly improve alignment and comfort.

    Professional Recommendation: Start with a comprehensive assessment before ordering custom shoes. Combine gait analysis, 3D foot scanning, and lifestyle discussion (weekly mileage, race goals, injury history) to create a holistic profile. This ensures your customized running shoes aren’t just comfortable—but performance-enhancing and injury-preventive.

    Runner Profile Recommended Custom Features Best Midsole Type Key Benefits
    Recreational jogger (3–5 miles/week) Light arch support, standard width, padded collar EVA foam Comfort, affordability, everyday durability
    Marathon trainee Custom insole, enhanced cushioning, breathable upper Pebax or Boost Energy return, reduced fatigue, blister prevention
    Overpronator with flat feet Motion control insert, firm medial post, structured upper Dual-density EVA Improved alignment, reduced knee/ankle strain
    Trail runner Aggressive outsole, protective toe cap, waterproof membrane Durable rubber compound + cushioned midsole Traction, foot protection, stability on uneven terrain

    Additional Considerations for Custom Running Shoes

    • Break-In Period: Even perfectly fitted custom shoes may require 10–20 miles to fully adapt to your foot’s pressure patterns
    • Replaceability: Check if custom components (like insoles) can be replaced separately to extend shoe life
    • Warranty & Adjustments: Reputable providers offer follow-up fittings and minor adjustments post-delivery
    • Climate Adaptability: Consider ventilation options for summer runs or insulated liners for cold-weather training
    • Sustainability: Some brands now offer eco-friendly custom shoes made from recycled materials without sacrificing performance

    Scenarios of Custom Running Shoes: Tailored Performance for Every Runner

    Custom running shoes are no longer just a luxury—they're a performance necessity for runners across disciplines. Designed to meet individual biomechanical needs, these personalized footwear solutions enhance comfort, reduce injury risk, and optimize efficiency. Whether you're training for a marathon or recovering from an injury, the right custom shoe can make all the difference. Below, we explore key running scenarios where customized footwear delivers measurable benefits.

    1. Long-Distance Running

    Custom running shoes are indispensable tools for serious long-distance runners. Unlike off-the-shelf models, they are engineered to match your unique foot shape, arch type, and gait pattern. This precision fit significantly reduces foot fatigue, joint strain, and common overuse injuries such as plantar fasciitis and Achilles tendinitis.

    For marathoners and ultra-runners, every mile counts. Custom shoes with personalized insoles, cushioning profiles, and upper materials ensure consistent support over extended distances. The result? Improved endurance, fewer pressure points, and a more enjoyable running experience. In professional running, where margins matter, custom footwear is not just beneficial—it’s essential.

    Pro Tip: Long-distance runners should consider dynamic gait analysis when designing custom shoes. This ensures the shoe adapts to your foot’s movement throughout the entire stride cycle, not just at rest.

    2. Treadmill Training

    While treadmill running offers a controlled environment, it also involves repetitive motion on a consistent surface—increasing the risk of overuse injuries. Custom running shoes help mitigate this by providing targeted support where you need it most.

    Runners can integrate specialized insoles that correct pronation or supination, and choose midsole materials that enhance shock absorption. These customizations reduce repetitive strain on the feet, knees, and hips during prolonged treadmill sessions. Additionally, breathable uppers and moisture-wicking linings prevent discomfort caused by sweat buildup during intense indoor workouts.

    For athletes training indoors year-round, custom shoes offer a biomechanical advantage that standard models often lack, ensuring each stride is as efficient and injury-free as possible.

    3. Trail Running

    Trail runners face unpredictable terrain—from rocky ascents to muddy descents and uneven surfaces. Standard running shoes may not provide adequate protection or stability in such conditions. Custom running shoes for trail use are designed with your foot’s unique structure in mind, minimizing blisters, hot spots, and instability on technical trails.

    Key custom features include:

    • Enhanced Traction: Outsoles tailored to your stride and terrain preference (e.g., deep lugs for mud, aggressive grip for rocks)
    • Debris Protection: Custom-fitted gaiters or sealed uppers to keep dirt and stones out
    • Durability: Reinforced materials in high-wear areas based on your foot strike pattern
    • Ankle Support: Modified heel counters or collar padding for uneven ground stability

    These personalized elements ensure both comfort and longevity, allowing trail runners to focus on the path ahead—not foot pain.

    Expert Insight: Consider climate-specific customization—water-resistant membranes for wet trails or ventilated mesh for hot, dry environments—to further enhance performance.

    4. Recovery Running

    For runners rehabilitating from injuries like shin splints, stress fractures, or plantar fasciitis, returning to running requires caution and proper support. Custom running shoes play a vital role in recovery by providing biomechanical alignment, impact reduction, and targeted cushioning.

    Features such as anti-shock insoles, medial or lateral posting, and graduated midsole density help offload stress from injured areas. These modifications allow runners to maintain aerobic fitness during recovery without aggravating existing conditions.

    Moreover, as running culture increasingly embraces the idea of movement as medicine, more athletes are turning to custom footwear not just for performance—but for long-term joint health and injury prevention. Whether managing chronic conditions or rebuilding strength post-injury, custom shoes offer a safe, supportive foundation for low-intensity, therapeutic runs.

    Important Note: Always consult with a sports medicine professional or podiatrist before resuming running post-injury. Custom shoes should complement, not replace, a structured rehabilitation plan.

    Running Scenario Primary Benefits of Custom Shoes Recommended Custom Features Ideal For
    Long-Distance Running Reduced fatigue, improved endurance, injury prevention Personalized arch support, energy-return midsoles, seamless uppers Marathoners, ultra-runners, competitive athletes
    Treadmill Training Shock absorption, comfort during repetitive motion Cushioned midsoles, breathable materials, gait-specific insoles Indoor trainers, fitness enthusiasts, rehab patients
    Trail Running Stability, protection, durability on rugged terrain Aggressive outsoles, reinforced uppers, ankle support Adventure runners, mountain athletes, off-road enthusiasts
    Recovery Running Impact reduction, alignment correction, joint protection Anti-shock insoles, orthotic integration, soft landings Injury rehab, chronic condition management, older runners

    Why Customization Matters Across All Disciplines

    No two feet are alike—and neither are two running styles. Off-the-shelf shoes are designed for averages, but custom running shoes are built for you. From elite performance to injury recovery, the ability to tailor fit, support, cushioning, and durability ensures that every runner can achieve their goals safely and comfortably.

    Investing in custom footwear is an investment in your long-term running health. Whether you're logging miles on pavement, conquering mountain trails, or rebuilding strength after an injury, the right custom shoe provides the foundation for success.

    Frequently Asked Questions About Custom Running Shoes

    Q1: What Are Custom Running Shoes?

    Custom running shoes are precision-engineered footwear designed specifically for an individual’s unique foot structure, gait pattern, and performance needs. Unlike off-the-shelf models, these shoes are crafted using advanced technologies such as 3D foot scanning, pressure mapping, and biomechanical analysis to ensure a perfect fit and optimal support.

    • Personalized Fit: Captures the exact contours of your feet, including arch height, width, heel shape, and toe box space.
    • Built-In Support: Addresses biomechanical imbalances like overpronation or supination with targeted structural reinforcements.
    • Enhanced Performance: Improves running efficiency by aligning your stride, promoting better posture, and reducing energy loss.
    • Injury Prevention: Minimizes stress on joints, tendons, and muscles by distributing impact forces evenly across the foot.

    Whether you're a professional athlete or a recreational runner, custom shoes offer a level of comfort and functionality that mass-produced footwear simply can't match. They're especially beneficial for individuals with chronic foot pain, previous injuries, or anatomical irregularities.

    Q2: How Important Is Cushioning in Custom Running Shoes?

    Cushioning is a critical component of custom running shoes, playing a key role in shock absorption, joint protection, and overall running comfort. Unlike standard shoes that use one-size-fits-all foam densities, custom shoes feature tailored cushioning based on your running style, weight, terrain preferences, and foot strike pattern (heel, midfoot, or forefoot striker).

    • Impact Reduction: High-density or adaptive foams absorb up to 30–50% more impact than standard materials, protecting knees, hips, and lower back.
    • Zoned Cushioning: Different areas of the sole can be customized—softer under the heel for shock absorption, firmer in the forefoot for propulsion.
    • Long-Distance Comfort: Reduces fatigue during extended runs by minimizing repetitive stress on sensitive areas like the plantar fascia.
    • Pain Management: Ideal for runners with conditions like plantar fasciitis, shin splints, or arthritis who need extra padding in specific zones.

    Experts often combine dynamic gait analysis with pressure plate testing to determine the ideal cushioning profile, ensuring that each step feels smooth, stable, and supported.

    Q3: Who Can Benefit from Custom Running Shoes?

    While all runners can enjoy the advantages of a personalized fit, certain groups gain exceptional benefits from custom footwear:

    • Runners with Foot Conditions: Individuals with flat feet (overpronation), high arches (supination), bunions, hammertoes, or neuromas benefit from corrective support and pressure relief.
    • Recreational Athletes: Weekend joggers or fitness enthusiasts seeking enhanced comfort and reduced injury risk during training.
    • Competitive Runners: Marathoners and triathletes who demand peak performance, durability, and efficiency from their gear.
    • Post-Injury Recovery: Those rehabilitating from stress fractures, Achilles tendonitis, or ankle instability can use custom shoes to offload affected areas safely.
    • People with Asymmetrical Feet: When one foot differs significantly in size or shape from the other, custom shoes provide balanced support.

    Additionally, older adults or individuals with diabetes may require custom shoes to prevent ulcers and maintain mobility. The personalized nature of these shoes makes them a valuable tool for both performance enhancement and long-term foot health.

    Q4: How Are Custom Running Shoes Different from Regular Running Shoes?

    The primary difference lies in personalization versus generalization. While regular running shoes are designed for broad foot types and average biomechanics, custom running shoes are built from the ground up for your unique physiology and running mechanics.

    Feature Regular Running Shoes Custom Running Shoes
    Fit Standard sizes and widths; may require insoles or modifications Fully tailored to exact foot dimensions and volume
    Support Generic arch support; limited adjustability Biomechanically engineered support based on gait analysis
    Cushioning Uniform density across models; varies by brand Zoned, personalized cushioning matched to strike pattern and weight
    Materials Premade fabrics and midsoles for mass production Selected based on individual needs—breathability, flexibility, durability
    Performance Good for general use; compromises for versatility Optimized for efficiency, comfort, and injury prevention

    Custom shoes eliminate the guesswork of finding the "right" model and instead deliver a precise solution that enhances every aspect of your run—from comfort and stability to speed and endurance.

    Q5: How Do I Care for My Custom Running Shoes?

    Proper care extends the life of your investment and maintains the integrity of the customized components. Since these shoes are made with specialized materials and structural elements, maintenance should be thorough yet gentle.

    • Clean After Use: Wipe off dirt and mud with a damp cloth after each run, especially if used on trails or wet surfaces.
    • Washing: Hand wash with mild soap and lukewarm water when needed. Avoid machine washing, which can damage adhesives and cushioning layers.
    • Drying: Air dry at room temperature—never place near radiators, heaters, or direct sunlight, as heat can warp midsoles and shrink uppers.
    • Storage: Keep in a cool, dry, well-ventilated area. Use a breathable shoe bag to prevent dust buildup and moisture retention.
    • Rotation: If possible, alternate between two pairs to allow each to decompress and dry fully between uses.
    • Insoles and Liners: Remove and air out regularly to prevent odor, bacterial growth, and moisture accumulation.
    • Dedicated Use: Wear your custom shoes only for running—not for gym workouts, walking long distances, or casual wear—to reduce unnecessary wear and preserve performance features.

    With consistent care, custom running shoes can last 500–800 miles while maintaining their supportive and responsive qualities. Periodic check-ins with your footwear specialist can also help identify when components need refreshing or replacing.