Allows air cleaners with 1/4" stud and wing nut to be used on carburetors with a 5/16" mounting hole. One end of the adapter features a 5/16"-18 male thread that screws into the carburetor. The other end features a 1/4"-20 female thread that accepts a standard air cleaner mounting stud. Clear zinc plating resists corrosion. Overall length: 7/8".