One-Touch push-to-connect configuration allows an instant tubing connection. Smooth-Edge release sleeve design facilitates a quick tubing disconnection Aesthetically pleasing nickel-plated metallic optional feature ensures anti-containation properties of an extended product lift. Pre-applied sealant on all external threads eliminates the additional sealing requirement. Internal and/or external flat-to&flat hexagonal configurations for both metric and inch specifications allow a proper tightening or directional orientation upon installation by using L key or allen wrench for the applicable model types. http://www.idealbell.com