This is a A-RBX1-12 X Hub PN: RBX1-12Main Description As Following : A-RBX1-12 X Hub P.N: RBX1-12 Dim A (1): 2"Dim B (2): 2-1/2"Dim C (3): 7/16"Dim D (4): 1"Bore: 1-1/2" roundKeyway: 3X8" X 3/16" Crossed From: WSH30024 , , 20030024 , , 3016-0136 , , 6713-59213 JOHN DAY , 673-S80031900 , , 673S80031900 , Found in Section & Models : Chains/ Sprockets/ Pulleys/ Hubs > Hubs, (Miscellaneous) (UNDEFINED): SEVERAL Associated Items : New Also This is An Aftermarket Product And : Dim A (1): 2" Dim B (2): 2-1/2" Dim C (3): 7/16" Dim D (4): 1" Bore: 1-1/2" round Keyway: 3X8" X 3/16"