The FUTURUM 4 SEASONS Merino Socks Extra Warm have been developed for the cold days. There are lines are visible on the outside, giving the socks the appearance of aero socks. These lines are made of merino wool and this thicker layer offers extra comfort. On the inside of the sole a "terry mesh" structure has been applied. This mesh provides a pleasant extra warmth, but also has plenty ventilation capacity. The addition of polyamide on the heel and toes makes the socks extremely strong. The soft merino wool does not itch or shrink and the flat seams do not start to irritate on longer rides. Merino wool is self-cleaning and moisture-regulating, which keeps your feet feeling comfortable and fresh.