Springfield Marine's 1100521-L1 Trac-Lock Locking Slide and Swivel features a 2-7/8" post mount with bushing for a close fit. It is a 7-1/4" x 13" locking seat mounting platform and is constructed of high-strength aluminum to withstand harsh marine environments. This slide and swivel seat mount travels 5-1/4" forward and backward on self-lubricating pads and rotates up to 360 degrees. It adds 1-1/4" of height and can be used with any 2-7/8" fixed height pedestals. Centrally located locking handle is easy to reach with left or right hand.