This is a A-40X25 Sprocket PN: 40X25Main Description As Following : A-40X25 Sprocket P.N: 40X25 Hub Required: XInside Diameter: 2"Outside Diameter: 4.258"Teeth: 25 Crossed From: WSS104025 , , 20004025 , , 20004025 , , 2827-38827 JOHN DAY , 3016-0153 , , 6713-50463 JOHN DAY , 673-S80402500 , , 673S80402500 , Found in Section & Models : Chains/ Sprockets/ Pulleys/ Hubs > Sprockets, (Miscellaneous) (UNDEFINED): SEVERAL Associated Items : New Also This is An Aftermarket Product And : Hub Required: X Inside Diameter: 2" Outside Diameter: 4.258" Teeth: 25