Special pocket sewn in above the toes to hold Heat Factory Foot Warmers (Warmers sold separately) * Compression fitting; comfort heel design; above knee length for use with waders * 43% Merino wool, 35% acrylic, 7% Nylon, 11% polyester, 3% rubber, 1% Spandex * Size large only; fits men"s US shoe sizes 8.5 - 13 * Made in USA