Connect 3/4 inch camlock coupling to 3/4" BSP tapered (R3/4 / BSPT)

A 3/4 inch cam-and-groove coupling has no thread of its own, so it reaches a R3/4 (tapered BSP (BSPT)) port through a same-size threaded camlock adapter: a Type A male adapter or a threaded coupler carrying the R3/4 thread on its back. That thread is a tapered, 55 degree form of 26.441 mm major diameter at 14 threads per inch and seals on the thread flanks with PTFE tape or paste; the cam end then mates to its opposite 3/4 inch camlock half.

The 3/4 inch cam profile and the R3/4 thread are two separate choices. A correct R3/4 back thread still leaves you with the wrong front if the half you mate to is not the matching 3/4 inch cam type, so confirm both the size and the A-to-F type before buying.