Bomar Commercial Grade Aluminum Inspection Hatch 9-1/4 inch Round Single-Dog Low Profile. Hatch is made of Almag-35 Aluminum and has removable lid for easy access. Locks down with a single t-handle. Non-skid surface. Hatch Opening: 9-1/4 inches (235 millimeters), Outside Deck Flange: 12-1/2 inches (318 millimeters), Cutout: 10-1/4 inches (267 millimeters), Extends below deck: 1/2 inch (13 millimeters), Weight: 4 pounds.