Johnny Ray Swivel Mounts feature simple, one-handed operation which securely holds your unit in place, no matter what the boating condition is. No clumsy knobs to tighten, or multiple joints to move. Plus they keep your Electronic Unit close to the boat, not out on a limb where vibration and rough water can make viewing your unit virtually impossible. Features of the JR-300: Swivel Top Hole Pattern Measures 5 -1/2 inches x 1-1/4 inches. Low Profile û 1 inch tall. 45 Position Automatic Locking Top. Push-Button Top Release Mechanism. Molded from DuPont Nylon and assembled with Stainless Steel Springs and Screws.