The Smartwool Run Zero Cushion Low Ankle Socks are built for runners who want absolute minimal bulk and maximum ground feel. Stripped down to a zero-cushion profile, these ultralight socks fit perfectly into snug racing flats or low-volume running shoes. Featuring a targeted merino wool blend and an integrated Achilles tab, they offer unparalleled breathability, sweat management, and blister protection for high-output efforts on the track, road, or trail.

Specs & Features

​Technical Specs

• ​Model Number: SW001651
• Color: Black (#Actual color may vary) 
• Height: Low Ankle (Sits just below the ankle bone but includes a protective heel tab)
• ​Cushioning: Zero Cushion (The absolute thinnest profile for maximum breathability and shoe volume)
• ​Material Composition: ~46% ZQ-certified Merino Wool, 49% Nylon/Recycled Nylon, 4% Elastane, 1% Polyester

​Key Features

• ​4 Degree™ Elite Fit System: A dual-elastic support system that wraps around the arch and instep, locking the sock firmly in place to prevent internal friction.
• ​Indestructawool™ Technology: Features extended durability zones that reinforce the entire sole, ensuring this ultralight sock can withstand high-mileage abuse.
• ​Shred Shield™ Technology: Greatly reduces wear from toenails, extending the life of the toe box.
• ​Virtually Seamless™ Toe: Eliminates the bulky internal seam at the front of the foot, preventing chafing during repetitive, high-impact strides.
• ​Achilles Tab: A raised heel tab prevents the shoe collar from rubbing your skin and stops the sock from slipping down into your shoe.

​Care Instructions

​To keep these ultralight performance socks in prime condition:

• ​Wash: Machine wash warm or cold on a gentle cycle. Wash inside out to flush away dead skin cells and sweat salts. Wash with similar colors.
• ​Detergent: Use a mild liquid detergent. Never use fabric softeners or bleach, which coat the merino fibers and ruin their natural wicking capabilities.
• ​Drying: Tumble dry on low heat, or line dry in the shade to protect the precise elasticity of the 4 Degree™ Elite Fit system.
• ​Ironing/Dry Cleaning: Do not iron. Do not dry clean.

​X-Boundaries Professional Tips

• ​The Race-Day Go-To: If you wear tightly tailored carbon-plated racing shoes or track spikes, zero-cushion socks are a must. They prevent your feet from feeling cramped while still providing the moisture-wicking benefits of merino wool.
• ​No-Slip Heel Security: The "Low Ankle" cut combined with the Achilles tab is the perfect compromise for runners who hate the look of taller socks but constantly suffer from "sock slip." The tab acts as a physical anchor over the back of your shoe.
• ​Summer Heat Management: Don't let the word "wool" fool you. Ultralight, zero-cushion merino is one of the most effective fabrics for hot-weather running. It actively pulls moisture vapor off your skin before it condenses into sweat, keeping your feet significantly drier than traditional synthetic socks.