Mist’n Go, Inc is offering the Modular Combat Cooling System (MCCS) first deployed with US troops in 2003. An upgraded vest was introduced in 2005. MCCS provides a two tier system, covering the thorax, head, neck and arms. It is worn under standard military body armor. The vest has detachable sleeves which allow wearing an OTV directly on top of the cooling garment, which is worn over the T-shirt. The system’s design allows for exchange of rear packs while on patrol, without removing the protective OTV. The torso represents the main heat-sink for managing the core body temperature. To control the greatly increased heat stress from interceptor OTV armor, phase change packs are attached to the cooling vest’s pockets, maintaining a constant temperature of 58 degrees for over hours. Head cooling is provided by an evaporative cooling beanie cap. When worn under a helmet, phase change packs are added inside the helmet.