Bomar locking deck plates are made of marine grade, ultra-violet (UV) stabilized resin that won't fade or discolor from prolonged exposure to sunlight. Deck plates utilize an internal O-ring seal to lock out moisture, and plate centers lock to secure when not in use. Inside Diameter: 5-3/16" Outside Diameter of Ring: 8-3/8" Cutout Diameter: 6-3/8" Type: T-Handle Locking Center