Fits into existing 5-speed cases; lowers the rpm at cruising speeds. 6-speed gear set (3.24:1 1st gear/.86:1 6th gear), 28-tooth motor sprocket, longer primary chain, adjusting shoe, fixed spindle-shift drum and anti-overshift ratchet shift pawl assembly. All gears are full-width Baker ground gears; 4th, 5th and 6th gears are helical for silent operation. Includes easy-to-follow instructions. Bearing door is manufacturered from 6061-T6 Aluminum and features wider bearings and a bearing retainer plates instead of the stock style snap rings. Redundant Neutral Smooth Shift System. Gearsets are made out of 8620 steel, gears are cut before heat treating then precision ground with a diamond coated tooling for quieter operation.. Made in the U.S.A..