The castelli incendio 15 socks are constructed from a primaloft and wool blend for optimal warmth in cold winter cycling conditions the terry cloth pad under the forefoot provides added insulation and comfort the thin construction ensures the socks fit perfectly in summer cycling shoes while the 15cm cuff offers extra ankle protection complete with castelli branding key features castelli incendio 15 socks primaloft and wool blend terry cloth pad under the forefoot for extra war