JT Sprockets (JTSK2013 520X1R Chain and 14 Front/45 Rear Tooth Sprocket Kit Fits: Kawasaki EX250 Ninja 250R 88-07 Kit contains: 14 tooth chromoly front sprocket; 45 tooth steel rear sprocket; and JT 520X1R-106 link chain SCM415 chromoly steel alloy is used for the front sprocket, and ultra-durable high carbon C49 steel for the rear sprocket JT X1R Heavy Duty Chains are constructed with quad riveted pins for an extra strong rivet that resists powerful lateral forces on the outer plate X-Ring seals are used for a better seal and produce less friction than conventional O-ring chains