Stainless Steel 304 Cast Pipe Fitting, Cap, Class 150, 1-1/2" NPT Female Cap for closing the end of a pipe Female National Pipe Taper (NPT) threads for connecting to male pipes Made of stainless steel 304 for greater strength than 302 grade steel Lower carbon content for greater resistance to corrosion Class 150 fittings conform to standards ANSI B1.20.1 and ISO 49 for quality assurance