Renthal 16-17 KTM 250 EXC/ 300 EXC Rear Twinring - Black 520-50P TeethRenthal Twinring motocross rear sprocket was developed as the ultimate dirt bike rear sprocket for those looking to ride more and work less. The unique, dual material design combines a hardened steel outer chain ring that is heated to 200degreeC before being permanently fitted to our Ultralight aluminum inner, creating a permanent bond for the life of the sprocket. This Part Fits: Year Make Model Submodel 1993 2018 KTM 125 SX Base 2007 2008 KTM 144 SX