This is a A-HXE24567 Cap, Row Unit Idler Sprocket PN: HXE24567Main Description As Following : A-HXE24567 Cap, Row Unit Idler Sprocket P.N: HXE24567 Inside Diameter: .510"Outside Diameter: 1.830" Found in Section & Models : Headers/Platforms/Feeder House > Corn Head Parts, John Deere HEAD, CORN: 606 (SN 745101>), John Deere HEAD, CORN: 608 (SN 745101>), John Deere HEAD, CORN: 612 (SN 745101>), John Deere HEAD, CORN: 616, John Deere HEAD, CORN: 618 Associated Items : New Also This is An Aftermarket Product And : Inside Diameter: .510" Outside Diameter: 1.830"