This Attwood Deck Plate Inspection Port opens easily with no tools required to permit inspection and access to valves, deck vents, or storage spaces. Once the flange is installed, the lid screws in without tools, and it can be opened just as easily for access and inspection. It is made of high-impact ABS plastic to withstand the rigors of a marine environment. It has a textured surface and is weather-resistant. It has a 4-inch diameter and the flange is pre-drilled with six holes for installation using #8 fasteners. Attwood Corporation has been an award-winning leader in engineering, testing, and manufacturing the highest quality marine products for over 100 years. We deliver safe and reliable lighting, fuel systems, water systems, seating & pedestals, swim ladders, custom upholstery, and general marine accessories that are easy to install and meet regulatory compliance.