What are 3/4 and 7/8 Taper Thread Plugs?

"3/4" Taper" describes the diametrical taper of 3/4" per 12" of length of standard tapered pipe plug threads.

3/4 Taper is applicable to SAE, ASME/ANSI, DIN, British, and Japanese Standard tapered pipe plug threads.

"7/8 Taper" describes the diametrical taper of 7/8" per 12" of length of tapered flush seal PTF - 7/8 pipe plug threads.