From SmartWool, these socks feature: Indestructawool™ technology with extended durability zones 4 Degree™ elite fit system for a dialed-in, performance oriented fit Mesh zones for added breathability Virtually Seamless™ toe for enhanced comfort Achilles tab prevents sock from slipping into footwear Merino wool/nylon/recycled nylon/elastane One size fits most men's shoe sizes 9-13  Machine wash/tumble dry Made in the USA.