3/8″ copper tube size, quick connect elbow, hold up to 250 psi, 1 piece, no parts to assemble or lose, quick connect design allows quick & easy connections without the use of installation tools, great for new installations or plumbing repair projects for pex, copper, & cpvc pipe, just cut pipe & push pex, copper or cpvc tubing into fitting end until tubing seats at stop, can be disconnected by pulling back on ring & releasing pipe, code approved for behind wall without access & direct in ground burial installations, nsf-14, nsf-61, csa/astm & upc code listed & approved, excellent replacement for qest & flare it type fittings.