Wise 8WD14 Jon Boat Clamp with Swivel is the most popular swivel for boaters. Mounts on any flat boat seat bench up to 20-Inch deep. Adjusts 8-Inch to 20-Inch. Comes with 6.25-Inch Diameter steel swivel to fit all 5.25-Inch hole pattern brands of boat seats. Constructed of steel adjustment rods, plastic injection molded stabilizers, Plastic dipped rods to provide tacky grip to bench sidess. Comes with saftey clip. 3 year warranty.