This 4 inches screw-in deck plate is made of anti-aging, anti- and UV-resistant plastic with smooth . Deck Plate is leak-proof. SCREW-IN style has a single-start, non-jamming (no -threading). Separate cover plate and chassis for easy installation. Screws not included. Use silicone sealant on the hull or deck when installing the deck plate. Marine Round Inspection Deck Plate Hatch Material: plastic Color: White : Smooth Inside Diameter: 4 Inches Separate cover plate and chassis, very easy to install Package Contents: 1 x boat hatch cover Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.