WSM is a thick, high trekking winter sock made of double-layer plush (1) containing merino wool, which is a unique natural material that generates heat when wet, thus providing excellent thermal insulation and moisture removing properties. A simple instep bond improves foot ventilation and overall heat balance (2). The toe and the heel sections are reinforced with protection zones, which provide comfort when walking and long durability of the most stressed areas (3). Elastic is fitted around the instep area (4).