AG-5 - 1-1/4" Air Gap Adaptor FittingSpecification Sheet Zurn AG 5 1 1 4" to 2" Air Gap Adaptor Fitting The AG 5 Air Gap Fitting is used for indoor installations of all 1 1 4" 2" Model 975XL 975XL2 Reduced Pressure Principle Backflow Preventers for the connection of a drain pipe to the backflow preventer, directing nuisance water discharge to a safe drain. It has iron inlet and 2" NPT outlet connections. The AG Air Gap Fitting can be mounted to the body of any drain line made of any