INCLUDING - Comes with 1 female threaded connector and 1 female threaded connector and 4 male connector, male connector and 4 female connector, male connector. For air tools, air compressors, air hose set. FUNCTION - Spring loaded quick couplers for use on the compressor side have a built-in valve to shut off the air when switching from one tool to another. Nickel plated finish for rust and corrosion resistance. SIZE - 1/4" BSP. 12mm hex clamp (male fitting) 16mm hex clamp (male fitting) 19mm hex clamp (female/male fitting) Type: Male/female fitting, male/female thread. DESIGN - Simple to use, simply slide the collar back and insert the fitting, then slide the collar all the way back to lock. Allows tools and airlines to be quickly connected/disconnected. ADVANTAGE - Made of heat treated hardened steel. Spring loaded quick couplers for compressor side use have a built in valve to prevent air from escaping when changing tools.