The Advantage Flush Mount is the most unique flush mount on the market. It incorporates a positive double cam lock, which ensures a quality hold on your gear, and is easily released with a unique push button lock. Many other manufacturers' products will fit into this mount as well. Comes with a rubber cap to keep the water out. Bolting dimensions are the same as most manufacturers' - making it simple to just replace the mount. Holds most manufacturers' products, too. Positively locks gear in place. Positioning every 30 degrees. Not recommended for use with the F051 Adjustable Extension Post. Requires a minimum of 1-5/8" hole size for the lock to function properly. USA Patent.: US 7,757,424B2 Dimensions: 4" x 2" x 2" Bolting dimensions: 1-5/16" x 3-3/16"