The Feelfree Seat Adjustment Kit is used in conjunction with the Feelfree Overdrive system. This easy to install kit lets you trim the seat fore and aft so you can find the perfect position for comfortable pedaling. Includes all instructions. Seat adjust kit fits all Feelfree Gravity seats Works in conjunction with Overdrive system Allows seat to trim forward and backward for perfect pedaling comfort Only for use if you are using the Overdrive system