2-1/2" NH fire hose thread (NST) (2-1/2-7.5NH)

Used on: US fire hydrants, fire department connections (FDC) and 2.5 inch attack lines.

The 2-1/2 inch NH thread is the standard hydrant and FDC connection under NFPA 1963: 7.5 TPI on a 3.0686 inch outside diameter. It is not a pipe thread and will not mate with a 2-1/2 NPT without an adapter.

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.