NST Coupling
Couplings are sets of connection devices that interconnect to additional lengths of fire hose, adapters and other firefighting appliances. Usually made of stainless steel or aluminium, couplings are available in a variety of types and sizes.
National Standard Thread, also known as National Hose (NH) thread, is one of the more common couplings used in fire equipment. The male and female straight (non-tapered) threads screw together and the connection is sealed with a gasket.