HARDENED STEEL: Made of heat treated hardened steel for strength and durability.Zinc plated finish for rust and erosion resistance. SP40 - Quick Release Coupler for 12*8mm hose PP40 - Bayonet Connectors for 12*8mm hose SPRING LOADED: Spring loaded quick release couplers which should Be used on the compressor so that the air is contained when the air tool is disconnected. PERFECT LOCK: When using the coupler(s) slide back the sleeve, push in the connector and then slide back the sleeve fully to lock in the connector., Manufacturer: Mgoodoo