JT Sprockets JTSK2054 520X1R2 Chain and 14 Front/45 Rear Tooth Sprocket Kit Fits: Kawasaki EX250F Ninja 250 R 88-07 Kit Contains: 14 tooth Chromoly Front Sprocket; 45 tooth Steel Rear Sprocket; & JT 520X1R2-106 Link Chain SCM415 chromoly steel alloy is used for the front sprocket, and ultra-durable high carbon C49 steel for the rear sprocket JT X1R2 Heavy Duty Chains are contructed 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