RFX Pro Series Armalite Rear Sprocket Yamaha YZ125 250 YZF250 450 99 24 Various Sizes Colour:Blue Total Volume 9L YZ250 21 23 Total Volume 9L 480 RR 20 23 Bike Year Pitch Part Number YZ 125 99 01 520 FXRS 31 48 YZ 125 05 20 520 FXRS 31 48 YZ 125 02 04 520 FXRS 31 49 YZ 250 02 05 520 FXRS 31 49 YZ 250 99 01 520 FXRS 31 50 YZ 250 05 20 520 FXRS 31 50 YZF 250 01 04 520 FXRS 31 48 YZF 250 05 11 520 FXRS 31 49 YZF 250 12 20 520 FXRS 31 50 YZF 400 99 520 FXRS 31 48 YZF 426 00 02 520 FXRS 31 48 YZF 450 03 04 520 FXRS 31 48 YZF 450 10 13 520 FXRS 31 48 YZF 450 06 09 520 FXRS 31 49 YZF 450 14 520 FXRS 31 49 YZF 450 05 520 FXRS 31 51 YZF450 15 20 520 FXRS 31 48 WRF 250 07 14 520 FXRS 31 50 WRF 250 01 06 520 FXRS 31 52 WRF 400 99 01 520 FXRS 31 50 WRF 426 00 02 520 FXRS 31 50 WRF 450 03 20 520 FXRS 31 50 Hex Drive location between inner & outer ring