Seadog Deck Plate ScrewOut 5" Black #SEA3371551OD: 63/4", Cutout 51/2''Molded to the highest standards using top quality UV stablizers and anitoxidents.Single start nonjamming extra strong buttress thread design eliminates jamming problems of multi start or fine thread deck plates.Screw out plates with water tight 'O' ring are recommended for use where internal pressure ( oil canning ) may... More