SPOC 5/16-04 is model number of 5/16" O.D connector with R, PT, BSPT 1/2 thread stainless steel hex socket head male straight push in air fittings, designed to be round shaped body with internal hexagon which makes it possible to be installed in the closely spaced, tightening with a hexagon wrench. 5/16" x R 1/2 stainless steel round male straight push to connect fittings are made entirely of high grade stainless steel material which can hold nylon tubing, PU tubing, PE tubing, Teflon tubing and transfer air, oil, water and weak corrosive fluids.