Fits Holley 4150 style carburetors with 9-5/16 inch center-to-center fuel inlet spacing. These fuel lines are not only great looking but are very functional. They incorporate a small, convenient 1-1/2 inch diameter fuel pressure gauge. The gauge is designed to read in 1/2 PSI (pounds per square inch) increments and has a range of 0-15 PSI. Inverted flare female inlet thread size 5/8-18.