Stainless Steel 304 Cast Pipe Fitting, Union, Class 150, 3/4" NPT Female Union for connecting and extending two male pipes Female National Pipe Taper (NPT) threads on both ends for connecting two male threaded pipes Made of stainless steel 304 for greater strength than 302 grade steel Low carbon content for greater resistance to corrosion Meets standards ISO 49 and ANSI B1.20.1 for quality assurance