Luxuriously soft dress socks made with performance spun yarn for comfort with the benefits of copper and comes in 4 colors to match your shoes or pants. Manufacturer offers unconditional guarantee. If you are not satisfied with this product, return it with a dated receipt to Aetrex Worldwide for a replacement pair or one of like value. Sizing for men: Medium fits men"s shoe size (USA) 4.5-8.5; Large fits men"s shoe size (USA) 8.5-12; Extra-Large fits men"s shoe size (USA) 12-15.