Springfield 1100521-L1 2-7/8-Inch Locking Trac-Lock Slide and Swivel ABYC Class: AD (H-31 Driver) 2-7/8 Post Mount With Bushing For Snug Fit Large 7-1/4 x 13 Seat Mounting Platform, Travels 5-1/4 Forward And Backward On Self Lubricating Pads, Rotates 360 Degree Centrally Located Locking Handle, Easy To Reach With Left Or Right Hand 5-year warranty