Description: 【Compact Size】: The overall size of Boat Seat Swivel Base is 24cmx33cm/9.45inchx12.99inch, and the connection port size is 17.3cmx17.3cm/6.81inchx6.81inch, which is easy to operate and store when not in use 【Stable Support】: Replacement Mount is equipped with a sturdy base support accessory to ensure your stability and safe during your sea adventures 【Sturdy Material】: Chair Accessories is made of aluminum alloy and nylon base to ensure durability and reliability 【Wave Protection Design】: Swivel Bracket has a wave protection design to ensure smooth sailing, and is a must have accessory for any fishing boat 【Universal Compatibility】: Although Seat Plate Stand is designed for boat chairs and chairs, they are also used for bar stools or other furniture, table stands, shop stools or truck swivel seat base replacements Size Chart: Overall size: 24cmx33cm/9.45inchx12.99inch Connection size: 17.3cmx17.3cm/6.81inchx6.81inch Package Includes: 1 Boat Seat Swivel Base Note: Please allow slightly errors 1-2cm/0.39-0.79inch differences due to manual measurement.