This air gaps for reduced pressure zone assembly, 1-1-4" to 3" series 009 and 909, 1-1/4" to 2" series 009M1, and 2" 009M2, provide an unobstructed, physical separation between the discharge end of a potable water supply line and an open receiving vessel. The installation of an air gap and drain line are recommended on reduced pressure zone assemblies. It can be installed vertically or horizontally (vent elbow required for vertical installation).