Cover holes to your fuel tank gauge, wiring system and other areas that you may need to access in the future wih these screw-in deck plates. The positive O-ring seal prevents moisture and dust from penetrating, and the overlapping lid makes them completely watertight. There are no visible mounting screws, the plates look as though they were originally part of the boat. Sizes: 4 Inside Diameter6 Inside Diameter8 Inside DiameterColors: Black, Polar White, Dark Gray. Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Deck Plates.