Our heaviest weight Alpaca sock. Alpaca (–better than wool) socks wick away moisture while keeping your feet cozy warm in winter. Alpaca wicks so well it is practically water proof. It insulates 30% better then Merino wool in any conditions warm-cold. Thermo-regulating. Silver technology means anti-microbial with no odor or sweat and it helps prevent athlete’s feet. 12″ “Over the Calf” styles. (Also, available as a 9″ crew sock.) Made in the USA.