Bomar Commercial Grade Aluminum Inspection Hatch 13-9/16 inch x 15-3/4 inch Rectangle 2-Dog Low Profile. Hatch is made of Almag-35 Aluminum and has removable lid for easy access. Locks down with two t-handles. Non-skid surface. Hatch Opening: 13-9/16 inches x 15-3/4 inches (344 x 400 millimeters), Outside Deck Flange: 18-1/8 inches x 20-1/8 inches (460 x 511 millimeters), Cutout: 15-11/16 inches x 17-5/8 inches (398 x 448 millimeters), Extends below deck: 1/2 inch (13 millimeters), Weight: 12 pounds. TAKES BOM-P100-51 GASKET @ 5 FT.