The MotoSport.com Vortex 520 Aluminum Sprocket And Chain Kit includes ONE Steel Countershaft (Front) Sprocket, ONE Aluminum Rear Sprocket, and your choice of ONE Premium Drive Chain, each with the following features: Sprockets / Chainwheels Included: Vortex Front Steel Sprocket: Made of the highest quality steel. Case hardened. Drilled lightening holes on most applications. Vortex Aluminum Rear Sprocket: 100% CNC machined with saber tooth grooves. Vortex patent pending design. Available in a variety of colors or PTFE black hardcoat, which bonds to the aluminum to create a more durable surface with less friction. 7075 T6 billet aluminum, lightweight for less rotating mass.