Smooth Quarter Turn Deck Plate - Black - 4" The Sea-Dog® Quarter-Turn Deck Plate is constructed of UV stabilized ABS. Features a new locking system that prevents over tightening, jamming, and cross threading. Easy to open and close. A specially engineered lubricated gasket is used in conjunction with a knife edge for a leak tested seal. Installs with six #8 FH fasteners (not included). Patent Pending. Avoid contact with acetone or strong solvents.