For use on all Concept2 Indoor Rowers. Replacement seat top. 12" wide, 10" deep, 1½" thick, with contours for pelvic bones and tailbone. Mounting screws (4) included. Original equipment on Model C, D, E and Dynamic Indoor Rowers. Can be retrofitted on all Model B and most Model A Indoor Rowers, replacing the original "kidney" shaped seat. See more info.