The Smartwool Performance Ski Zero Cushion OTC is a performance merino blend ski sock with minimal extra cushioning for minimal distance between your foot and boot. The sock uses a very light knit ensuring a good fit especially under tighter fitting boots. It also features 4 Degree Elite Fit System which uses two elastics for greater stretch and recovery so movement is kept free yet the sock will remain in place on your foot. Ventilation panels on the top of the foot prevent overheating retaining day long comfort inside a warm ski boot. Indestructawool Technology Indestrucatwool is a wool and yarn construction method used by Smartwool to create a wool and synthetic fibre blend which gives the best comfort and durability. 55% merino 41% nylon 4% elastane Smartwool Performance Ski Zero Cushion OTC