The Edelbrock #12602 Adjustable Inlet Needle and Seat assembly will fit carburetors with center hung fuel bowls and can be used as replacements or performance upgrades. Kit includes one locking screw, two gaskets and one O-ring. For use with Holley 2300, 4150, 4160, 4165, 4175 and 4500 Series, Quick Fuel 4500, Professional Series and Q-Series, as well as various Demon carburetors.