These Power-Lite crew socks will keep your feet dry and comfortable. The strike zone cushion provides maximum shock absorption for the heel and ball of your foot. The arch brace provides additional support. Medium fits womens shoe size 6 1/2-10 and mens shoe sizes 5-8 1/2. The large fits womens shoe sizes 10 1/2-13 and mens shoe sizes 9-12 1/2. Please note: Socks are not able to be returned or refunded if they have been removed from their original packaging.