Designed to replace broken flange(s) at the rear of the seat track. Each seat uses 2 flanges, and this kit provides 1, since often only 1 breaks. Those pieces were cast aluminum from the factory and fail under regular use. Here at C&S Corvettes, Ours are CNC machined out of billet aluminum so they never break! Our kit also includes the anti-rock washers that you will install while performing the flange replacement. Please specify R for passenger side, or L for driver side. See our other part numbers for other options.