Stainless Steel 304/304L Pipe Fitting, Flange, Threaded, Class 150, 2-1/2" NPT Female Flange for joining two pieces of pipe or connecting valves in a piping system Female National Pipe Taper (NPT) threads for connecting to male threaded pipes Bolt holes to connect to other bolted flanges or flat surfaces Made of stainless steel 304/304L for strength Meets standards ASTM A182 and ASME SA182 for quality assurance