Attwood Below Deck Adjustable Height Boat Seat Pedestal BaseThis Attwood boat pedestal base allows you to raise and lower your boat seat to your desired height. This durable pedestal can offers a height range from 9"-12" and accepts boat seat mounts with 2-3/8" diameter. When combined with other Attwood Air System mounts this pedestal provides superb stability for a smooth ride out on the water. This below deck boat seat mount required 2.75:" clearance below deck.