This is a A-RBX1-516 X Hub PN: RBX1-516Main Description As Following : A-RBX1-516 X Hub P.N: RBX1-516 Dim A (1): 2"Dim B (2): 2-1/2"Dim C (3): 7/16"Dim D (4): 1"Bore: 1-5/16" roundKeyway: 5/16" X 5/32" Crossed From: WSH30021 , , 3016-0133 , , 6713-58963 JOHN DAY , 673-S80031600 , , 673S80031600 , 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: 1-5/16" round Keyway: 5/16" X 5/32"