RFX Pro Series Elite Rear Sprocket Gas Gas MC EC 21 24 Various Sizes Teeth:52 feed tube routing can be Z Frame feed tube routing can be either over the shoulder or under the arm and cargo storage is 5 Bike Year Pitch Part Number CR 125 86 99 520 FXRS 10 51 CR 125 02 520 FXRS 10 51 CR 125 00 01 520 FXRS 10 52 CR 125 03 520 FXRS 10 52 CR 125 05 07 520 FXRS 10 52 CR 125 04 520 FXRS 10 53 CR 250 02 03 520 FXRS 10 48 CR 250 92 95 520 FXRS 10 49 CR 250 05 07 520 FXRS 10 49 CR 250 96 01 520 FXRS 10 50 CR 250 04 520 FXRS 10 50 CR 250 84 87 520 FXRS 10 51 CR 250 88 89 520 FXRS 10 51 CR 250 90 91 520 FXRS 10 53 CR 500 92 01 520 FXRS 10 49 CR 500 84 85 520 FXRS 10 51 CR 500 86 87 520 FXRS 10 51 CR 500 88 91 520 FXRS 10 51 CRF 230 05 13 520 FXRS 10 50 CRF 250 18 19 520 FXRS 10 48 CRF 250 10 520 FXRS 10 48 CRF 250 11 17 520 FXRS 10 49 CRF 250 04 09 520 FXRS 10 51 CRF 250 RX 2019 520 FXRS 10 48 CRF 250 X 04 19 520 FXRS 10 48 CRF 450 17 19 520 FXRS 10 49 CRF 450 04 16 520 FXRS 10 48 CRF 450 02 03 520 FXRS 10 50 CRF 450 RX 2019 520 FXRS 10 49 CRF 450 X 05 18 520 FXRS 10 51 XR 250 96 04 520 FXRS 10 48 XR 650 00 10 520 FXRS 10 48 Colour coded for each model of bike Tighter Tolerances improve performance