"The RapidAir 3/4in. MaxLine Union Fitting is designed to make installation fast and easy. 3/4in. MaxLine fittings are designed for high-demand air tool users and longer air line runs in large buildings. Compression style with double O-ring. Nickel-plated brass. Reusable. Pieces qty. 1, Coupler Size in. 3/4, Max. PSI 175."