Stainless Steel 304 Cast Pipe Fitting, Hex Locknut, Class 150, 1-1/2" NPT Female Hex locknut locks two threaded fittings into place for stability and reduced vibrations Female National Pipe Taper (NPT) threads for use with male threaded pipes and fittings Made of stainless steel 304 for greater strength than 302 grade steel Low carbon content to ensure greater resistance to corrosion Meets standards ANSI B1.20.1 and ISO 49 for quality assurance