First introduced in 2005, z-Start Pro was the first Auto-Clutch to give the rider manual clutch lever override capability and defined the ultimate in tunability to suit each rider's preferences and riding conditions. Well known in the offroad racing world as bullet proof and the tamer of the nastiest terrain imaginable. Faster Cornering Improved Traction Virtually Eliminates Stalling Better Starts Faster Lap Times Fully tunable to rider preference & terrain conditions Fully adjustable includes optional wave springs and ball bearings. CNC laser cut drive plates perfectly match the center clutch with continuous radius spine technology causing clutch loads to be evenly distributed over a greater surface area with more precise tolerances. Center clutch design with innovative fluid dynamic oil flow technology. 30-Day Demo Ride & Performance Guarantee: If after riding you do not agree that this Rekluse product has significantly improved your riding performance and fun factor, simply return it within 30 days of purchase for a full refund.