Garelick/EEz-In Adjustable Height Ribbed Standard Friction Lock Pedestal - 12"-17" Seat Raises Or Lowers, Locks At Desired Height 2-7/8" (7Cm) Diameter Stanchion Tube, 9" (23Cm) Diameter Base Plate Anodized Protective Finish Helps Prevent Saltwater Corrosion And Weathering 2-7/8" (7Cm) Diameter Ribbed Stanchion Tube, 9.25" (23Cm) Diameter 6 Hole Base Plate 12" - 17" (30 - 43cm) Adjustable height