Made from heat treated hardened steel for strength and durability. Zinc plated finish for erosion resistance. Spring loaded quick release couplings to be used on the compressor so that air is contained when the air tool is disconnected. When using the coupling(s) slide the sleeve, push into the connector and slide back the sleeve to fully lock into the connector. Allows tools and airlines to be quickly connected/disconnected. Reduces accidental airline disconnection., Manufacturer: DongDong store