Thorlon acrylic fibers are specially spun to maintain softness and resilience for comfort, blister protection and durability, while keeping feet cool and dry. * Thin cushioning in ball of foot and heel helps reduce impact, friction and blisters. * Extra padding at the ball of foot helps prevent calluses and foot fatigue. * 64% Thorlon acrylic, 30% nylon, 6% polyester. * Made in USA. Care: Machine wash inside out in lukewarm water. Tumble dry low. Fabric softener recommended.