61% US Merino Wool, 26% US Nylon, 3% US Lycra Spandex Made in USA U.S. Merino Wool: Merino wool is soft, itch-free, naturally odor- and bacteria-resistant, cool in the summer and warm in winter. We source our 100% U.S. grown merino wool exclusively from sheep raised by American farmers on American farms. Hidden Nylon Plaiting: Advanced construction that sandwiches stretch yarns between two layers of body yarn, hidden nylon plaiting creates a smooth exterior and a low-profile fit that is ideal for technical and sport socks. A side benefit of this modern knitting technique is its ability to incorporate complex patterns, open-weave zones, and intricate designs for increased performance and extra style. Bottom-of-Foot Cushion Zone: Found throughout our Sport collection and in some Hike models, bottom-of-foot cushioning adds shock-absorbing loop knit across the entire sole, from the toes to the heel. Cushioning here reduces impact from running and hiking, and the fitted instep won??t interfere with low-volume shoes. Half-Density Cushioning: On the inside of the sock, a terry knit loop every other stitch creates half-density cushioning to add softness and wicking performance without dramatically affecting sock thickness. Its lower density makes it ideal for casual socks. Seamless Toe Closure: Advanced knitting techniques create a totally flat connection in the toe box, reducing bulk and eliminating blister-generating friction.