The Helicopter Aircrew Breathing Device or HABD (also known as a HEED or SEA [1]) is a piece of military survival gear which was adopted in order to increase the chances of survival for embarked troops and aircrew trapped in an aircraft which has ditched (crashed into a body of water.) Similar in function to SCUBA gear, it consists of a small cylinder pressurized with atmospheric air and first stage regulator worn in a pouch on the user's flotation vest; a pressure gauge; an air hose and a special second-stage regulator (the part that delivers air via the user's mouth). The regulator is on-demand (it only delivers air when the user breathes in) and is designed to be highly rugged in order to survive impacts associated with emergency ditchings.