Trenton Pipe SS304-64240 Pipe Fitting, Class 150, Cast Stainless Steel Grade 304, Half Coupling, 4" NPT Female Threads A Half Coupling connects two pipes to each other Quality Precision Investment Castings made of 304 Stainless Steel to ASTM A351 Standards USA, Standard Taper Pipe Threads, NPT-Female, to ANSI B.120.1 Standards