Anyone working outdoors in cold, windy and wet conditions should choose their clothing based on the multi-layer system. Wearing several thin layers on top of one another provides better warmth than a single thick garment. Furthermore, the layering principle is a very flexible way of adapting to different outdoor and indoor conditions. Mobility, warmth and weather protection are the key functions of functional workwear. Built up layer by layer, functional clothing responds to temperature fluctuations and changing weather conditions. The aim is to keep the body at a constant ‘operating temperature’. Carefully combining individual garments per layer creates a highly functional system comprising a base layer, a thermal layer and a weatherproof layer, protecting not only against the cold, wind and wet, but also against overheating and sweating.