The Smartwool Unisex Run Zero Cushion Ankle Socks are engineered for runners who demand maximum breathability and a precise, uncompromised ground feel. Featuring a highly responsive, zero-cushion profile, these ultralight merino wool socks fit seamlessly inside low-volume running shoes. Equipped with advanced durability technologies and a dialed-in performance fit, they keep your feet cool, dry, and blister-free during everything from track sprints to ultra-endurance trail runs.

Specs & Features

​Technical Specs

• ​Model Number: SW001653
• Color: Military Olive (#Actual color may vary) 
• ​Height: Ankle (Sits just above the shoe collar for lightweight protection)
• ​Cushioning: Zero Cushion (The absolute minimum thickness for ultimate responsiveness and breathability)
• ​Material Composition: ~46% ZQ-certified Merino Wool, 49% Nylon, 4% Elastane, 1% Polyester (exact blends may vary slightly by production year)

​Key Features

• ​4 Degree™ Elite Fit System: A proprietary construction utilizing two elastics for greater stretch and recovery, keeping the sock locked firmly in place to prevent friction and blisters.
• ​Indestructawool™ Technology: A specialized knitting method that strategically reinforces high-wear areas, dramatically extending the lifespan of the sock without adding bulk.
• ​Shred Shield™ Technology: Significantly reduces wear and tear at the tip of the toe box.
• ​Virtually Seamless™ Toe: Eliminates irritating internal stitching across the toes for enhanced comfort in tight-fitting running shoes.
• ​Body-Mapped Mesh Zones: Maximizes ventilation and moisture management exactly where the foot naturally dumps the most heat.

​Care Instructions

​Maintain the high-performance elasticity and moisture-wicking properties of your running socks with these steps:

• ​Wash: Machine wash warm or cold on a gentle cycle. Wash inside out to clear sweat and debris from the internal knit. Wash with similar colors.
• ​Detergent: Use a mild detergent. Do not use fabric softeners or bleach, which coat the merino fibers and ruin their natural breathability.
• ​Drying: Tumble dry on low heat, or line dry in the shade to preserve the 4 Degree™ elastic system.
• ​Ironing/Dry Cleaning: Do not iron. Do not dry clean.

​X-Boundaries Professional Tips

• ​The Low-Volume Solution: Because these socks feature "Zero Cushion," they are the absolute best choice if your running shoes fit snugly or if you suffer from overheating. They add virtually no extra volume inside the shoe, allowing for a pure, responsive ground feel.
• ​Achilles Protection: The slight elevation of the ankle height provides a crucial physical barrier between your skin and the heel collar of your running shoes, preventing the dreaded Achilles blister on steep, aggressive ascents.
• ​Hot Weather Secret Weapon: While merino wool is famous for winter warmth, ultralight, un-cushioned merino is actually one of the best summer running materials on the market. It pulls sweat away from your skin as a vapor before it even turns to liquid, keeping you significantly cooler and drier than synthetic alternatives.