GENTEC® Quick Connectors provide fast, reliable, and easy setup for welding, cutting, and brazing applications. They ensure pressure-tight connections made in seconds.;; Built-in automatic reset check valves prevent reverse flow of gas by cutting off the gas under back pressure; Oxygen and Fuel gas models are not interchangeable in order to prevent wrong connections; Maximum working pressure: 29 PSI for fuel gases, 145 PSI for oxygen; Gas must be shut off at regulators when disconnected; Color-coded for fast, efficient, and safe handling; 9/16”-18 (B Fitting) connections for all models