3/8" male national pipe thread 3/8" coupler. Interchangable with most Automotive Standard series couplers and plugs produced by other manufacturers. Features zinc plated solid brass bodies and sleeves with stainless steel springs, hardened steel locking balls and valves, and Buna-N (Nitrile) seals. Precision machined bar stock construction provides resistance to the effects of mechanical shock in rugged applications.