Pneuflex's SPOC 04-01 is 4mm O.D tubing x R 1/8 male thread hex socket head male connector push in fittings made entirely of high grade 316 stainless steel that offers high corrosion and chemical resistance, used to connect 4mm pneumatic tubing to R, PT, BSPT 1/8 female thread inline. Hex socket head stainless steel male connector push to connect fittings' round body with hex socket allows them to be installed anywhere space is limited.