Stainless Steel 316 Cast Pipe Fitting, Hex Locknut, Class 150, 1" 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 from stainless steel 316 for strength Higher corrosion resistance than stainless steel 304 Meets standards ANSI B1.20.1 and ISO 49 for quality assurance