Lightweight, noncorroding, and durable. With an extra heavy "O" ring to ensure a watertight fit. To be installed in areas where internal pressure (oil-canning) is NOT present. Ideal for inspection compartments, for clean-out, or access to shut-off valves, back-up fasteners. 10" O.D. 7-5/8" I.D. 8-3/8" cut size.