Merit Brass 417B-16 Stainless Steel 304 Pipe Fitting, Square Head Plug, Class 1000, National Pipe Taper Thread Male (Pack of 25), 1" Square head plug for closing and terminating the end of a pipe Male National Pipe Taper (NPT) threads for use with female threaded pipes Made of stainless steel 304 for greater strength than 302 grade steel Square head for increased leverage and use with a wrench Meets standards ASTM A182, ASME SA182, and ANSI B16.11 for quality assurance