Wise 8WP21-18S Adjustable Boat Seat Pedestal 12" - 18" Wise adjustable Height Locking Pedestal is strong and durable Locking 2-7/8" seat mount with 360 degree swivel 2-7/8" diameter pedestal adjusts 12" to 18" in height Smooth, thick wall, polished anodized aluminum Wise Hardware features a three year warranty