Designed to turn stock 5-speed transmission into a 6-speedReduces vibration that creates wearCreates a more relaxing cruising speedAll gear sets use 2.94:1 close-ratio 1st gear that widens bike's speed range in 1st gear and lessens the rpm drop when shifting into secondOverdrive 6th gear (.86:1 ratio) lowers engine rpm by almost 475 at 75 mphGaskets and seals includedMade in the U.S.A.Requires speedometer sensor block-off plate kit if speedometer is not driven from transmission, then two block-off plates kits are required.Trap door extends 3/8'' farther to right than stock part. Alteration to some parts that attach to or around the trap door may be required.Requires speedometer be recalibrated.