The Extended Cold Weather Clothing System (ECWCS) is the US Military’s cold weather clothing layering system. Currently, the Gen III system has seven layers that will keep a soldier nice and toasty even in the harshest conditions. The philosophy behind the system is that the air trapped in between each layer will provide insulation and layers can be added and removed as needed. This system is sometimes referred to as the Extreme Cold Weather Clothing System or Extended Climate Warfighter Clothing System.