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. Kit Contains: 16 tooth Chromoly Front Sprocket; 47 tooth Steel Rear Sprocket; & JT 520X1R2-112 Link Chain. Fits: BMW F650 Dakar 99-00, F650 GS 99-07, F650 GS Dakar 01-05.