For Use with Center-Hung Fuel BowlsThese needle and seat assemblies will fit carburetors with center hung fuel bowls and can be used as replacements or performance upgrades. Kit includes needle and seat assembly two gaskets and oneo-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 carbs.