Stainless Steel 304 Pipe Fitting, Union, Class 1000, 1/4" NPT Female Union for connecting and extending two male pipes Female National Pipe Taper (NPT) threads for connecting 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 ASTM A182, ASME SA182, and ANSI B16.11 for quality assurance