These leak-proof ABS deck plates are sealed with an innovative gasket to assure a watertight seal. Even if the gasket is removed, Beckson"s patented back-up sealing wall leaves the plate watertight. Designed to provide access without the use of tools, with a single start non-jamming (no cross threading), extra strong, self-cleaning buttress thread. Clear plate models come with white flange rings and allows you to observe gauges or controls without the necessity of removing the center. Screw out plates should be used in compartments where a change in oil pressure or oil canning can occur.