These socks are the best and here's why: Alpaca fiber, with its hollow-core, traps air for better insulation in any weather. Alpaca is ohhh sooo soft and luxurious yet it's also incredibly strong, resilient, and lightweight. Alpaca can be processed organically, it's sustainable, and alpaca fiber is warmer than sheep wool, plus it breathes. Alpaca is a lightweight natural fiber, and therefore alpaca socks weigh less than other thermal socks. Alpaca is naturally hypoallergenic. Alpaca naturally wicks away moisture so there is less chance of smelly and sweaty feet. These alpaca socks have a reinforced toe and heal and are machine washable. We recommend to lay them flat to dry.