1 Inch Male NPTF x 1 Inch Male NPTF nipple used to connect two 1 Inch Female NPTF fittings together. The male NPTF (National Pipe Taper Fuel) thread is designed to create a tight, leak free seal when connected to female NPTF (National Pipe Taper Fuel) without the use of a sealant in high pressure (HP) applications.