10 Year Life Lawson 18” x 36” Suction Outlet Cover Open Area: 343.44 square inches Flow Rate Wall: 1496. Flow Rate Floor: 2080 Includes frame and hardware 2008 certified main drain grates and covers have a super flow rate and a unique top profile design that provides extreme comfort under foot. These large area main drain frames and grates actually begin at 18 inch x 36 inch and go up in size in 18 inch increments. The SuperFlow capacity starts at 2080 GPM; that is unmatched by the competition. Install end-to-end to accommodate higher flow rates. No additional support required. For single unblockable drains or multiple drain use. Features and Specifications: Wall or floor installation. ASME-2007 and NSF compliant. UV and strength tested under ASME A112.19.8M. Raised, cross-ridged profile for non-slip (and water penetration if blocked).