The Core-Spun 30-40 mmHg Knee High Compression Socks are often physician recommended to help improve circulation, prevent moderate swelling and relieve tired, achy legs. FEATURES 30-40 mmHg (the mean compression for an average ankle size) Ultra stretchy yarns make the sock easier to put on High-tech CoolMax or X-STATIC fibers wick away moisture for a dyer and more hygienic sock environment Comfort designed top is non-restrictive while staying in place all day Black color contain X-STATIC silver fibers for moisture wicking Reinforced, comfortable heel and toe Polyester/nylon/spandex styles are designed to help prevent edema, leg discomfort, and deep vein thrombosis for long distance travelers. LATEX-FREE fibers for soft, cool comfort 100% USA Made MATERIAL: Coolmax, Nylon and Lycra