Anvil 8700138707, Steel Pipe Fitting, Nipple, 1/2" NPT Male x 4-1/2" Length, Black Finish Nipple for joining two pipes or extending pipe length Male National Pipe Taper (NPT) threads on both ends for connecting female threaded pipes and fittings Made from steel for greater rust resistance than iron NPT threads for creating tighter seals than straight threads Meets specifications ASTM A53 and ASME B 1.20.1 for quality assurance