This GFB Pulley Kit comes with the crank, alternator and power steering pulleys as well as the belts needed for install. Having large heavy pulleys spinning takes away power that is better spent moving the car. This kit takes care of that by replacing the crank pulley with a smaller lighter version. On your average underdrive pulley kit your accessories all spin slower. GFB takes care of that issue by providing smaller lighter pulleys for the power steering and alternator so they will maintain their stock functionality.