This is a A-50X19 Sprocket PN: 50X19Main Description As Following : A-50X19 Sprocket P.N: 50X19 Hub Required: XInside Diameter: 2"Outside Diameter: 4.121"Teeth: 19 Crossed From: WSS105019 , , 20005019 , , 20005019 , , 2827-39927 JOHN DAY , 3016-0190 , , 6713-51813 JOHN DAY , 673-S80501900 , , 673S80501900 , 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: 4.121" Teeth: 19