The DeFeet AirEator is known as the "original air-flow sock" that leads in durability, wicking, drying, and air permeability.45% coolmax, 40% nylon, 15% lycraFits U.S. Men"s Sizes 7 - 9Fits U.S. Women"s Sizes 8.5 - 10.5Stayfast cuff provides a secure, durable, dynamic fitAirEator Vapor Zone - The DeFeet invention that started the "airflow" sock rageEn-Duro-Skin construction reinforces the external heel and toe, puncture areasAchill-E-Shield reinforces high-stress areaSolez system lets durability and wicking co-existMachine wash cold, tumble-dry low, no chlorine bleachItem SpecificationsColorWhiteMaterial45% coolmax, 40% nylon, 15% lycraSizeMediumSeasonWarm WeatherCuff LengthCalf, 5-6"Type of MaterialSyntheticDefined ColorWhite