Beckson Marine 4" Clear Center Screw Out Deck Plate - Black. They incorporate a self-aligning center and an innovative gasket to assure a watertight seal. A back-up sealing wall leaves the plate watertight even if the gasket is removed. Our clear center plates permit observation of controls or gauges and visual inspection without the necessity of removing the center. Deck plates are used for access to shut-off valves or back-fastenings inspection and clean out for tanks and compartments. A screw-out plate should be used in compartments where a change in air pressure due to temperature or oil canning can occur. Center: Clear Color: Black Specifications for Beckson Marine 4" Clear Center Screw Out Deck Plate: Manufacturer: Beckson Color: Black Package Contents: Beckson Marine 4" Clear Center Screw Out Deck Plate Beckson Marine DP40-B-C: 4" Clear Center Screw Out Deck Plate - Black