This kit is designed for the ones who want the most from their sleds in all conditions. Designed around racing, there is enough adjustment in the kit to use it for recreation or different levels of riders. The kit includes 1 race clutch , 1 quick change hub, A # 35 race chain, 2 sprockets, extra set of springs,and governor rod kit. Stock speeds are about 8MPH, this kit can boost speeds up to 18-20MPH depending on rider and conditions. Ski-Doo and Polaris kits also include a footwell screw kit. For Arctic, Ski-Doo & Yamaha we recommend a billet chain adjuster, (Part #430-214) this helps eliminate unnecessary wear, reduces friction and allows kit to perform to its potential.