seat base fits with the 3/4Inch boat pedestal post, Boat Seat Swivel, suitable for most boat seats. Whether you are heading for a fishing expedition or planning a leisurely boat ride, they are very convenient to use. The 7 x 7inch aluminum board seat pedestal is cast in one piece and is strong enough. Perfectly fitting the threaded boat seat post or boat seat mount base pin without shaking, ensuring safety. Our boat seat pedestals is made of aluminum alloy material, which is , robust, well built, easy to install. Boat seat base is designed to help add more safe and secure seating to your pontoon boat or fishing boat. Installation is easy and only takes a few minutes. Drill a hole larger than 2.3 inches through the center post and require a 2.5inch clearance below deck to flush with the mounting , then lock onto the deck to complete the installation. Colour:As Shown Material:ABS+Metal Package Contents: 1set * BOAT SEAT Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.