Rothco’s Mid-Weight Thermal Underwear Breakaway Bottoms feature hook and loop down the outside of each leg, enabling rapid removal when wearing boots. These warms bottoms are part of level two of the ECWCS (Extended Cold Weather Clothing System) utilized by the US Military since the 1980s. The moisture wicking material composition of the winter bottoms keeps you warm and dry, the bottoms also feature odor-defending grid fleece material. The elastic waist bands accommodate most body types.