A commonly used term for British Standard Pipe Parallel Thread (BSPP or BSPT). Suffix F for female; M for male. For specialty gases installations the most common size is 1/4". The sealing is obtained by a gasket between the fitting and component. In some applications, BSPP can be mixed with BSPT (British Standard Pipe Tapered Tread or R-thread) but this mix should be avoided in specialty gases installations due to the potential for gas leaks. Do not mix these fittings with NPT threads.