Vortex CK6272 520 SX3 Chain and Sprocket Kit Chain Size, 114 Front Teeth, 15 Rear Teeth, 45 Model, HFRA Material, Aluminum. Use RX3 or SX3 Vortex chains. HFRA “HYPER FAST” 520 KIT. Conventional Street kit with hard-coat aluminum rear sprocket. Gearing one down in front, two up in rear. HFRS “HYPER FAST” 520 KIT. Conventional Street kit with laser-cut steel rear sprocket. Stock gearing with laser cut steel rear sprocket. We Ride, We Race.