1-1/2" NH fire hose thread (NST) (1-1/2-9NH)

Used on: US fire hose, standpipes and some large transfer lines.

National Hose (NH), also called National Standard Thread (NST), is the default US fire connection defined in NFPA 1963. The 1-1/2 inch size runs 9 TPI on a 1.990 inch outside diameter and seals on a rubber gasket in the coupling swivel.

Quick-connect click fittings from Hozelock, Gardena and Karcher are proprietary and do not interchange. They all sit on top of a standard thread underneath, so the reliable way to move between brands is to adapt at the threaded tap or hose-end fitting, then use each brand's own connector above it.