The product is Air Brake-NTA Union Fitting, Brass, 3/8" Compression Tube x 3/8" Compression Tube. It features D.O.T. Compression style fittings for repairing truck and trailer air brake lines, For Use in air brake Systems on semi-trucks, trailers, buses, mobile equipment and farm implements, Ribbed sleeve for compression and positive grip, Stainless steel tube support, Meets D.O.T. FM's 571.106, SAE J246 and SAE J1131.