Nylon fiber is sturdy, after blending with Superwash Wool, this combination is durable and easy to care. The 75% Superwash Wool and 25% Nylon is a classic composition. We have two collections, Sock Premium is made of Superwash Meirno wool and Nylon, which is a next-to-shin softness; Sock Economy is made of Superwash wool (28micron Australia wool) and Nylon, which is durable and easy care with economy pricing. Both Sock Premium and Sock Economy have fingering and worsted weight.