Proflow Fuel Pressure Gauge Adaptor Fitting, Suits GM LS Engines, AN4 Female to 1/8'' NPT, Black, Each

This adaptor fitting allows you to adapt a fuel pressure gauge directly to the factory GM LS fuel rail. It screws into the end of the fuel rail (with the removal of the schrader valve) and converts it into a 1/8'' NPT for a gauge of your choice to screw into. It can also be used for other universal applications.