Five Oceans Marine White Screw-in Deck Plate, 4",5",6",8" MADE FROM UV-resistant ABS plastic THIS DECK PLATE is leak-proof. SCREW-IN style has a single-start, non-jamming (no cross-threading) A RUBBER O-RING on this screw-in deck plates creates a watertight seal for safety THE OUTSIDE Diameter is 8" (203mm), THE INSIDE Diameter is 6" (152mm) and THE CUTOUT is 6 3/8" (162mm) PLEASE, use silicone sealant on the hull or deck surface when installing the deck plate Material: UV-resistant ASA plastic Color: White Finish: Smooth Inside Diameter: 6&#034; Outside Diameter: 8 (203mm) Cutout Diameter:  6 1/2&#034; (165mm) Features: Coarse Thread w/ leak-proof function