Specification - R1200-Z - Large Sump Dexotex Roof Drain with Wide Deck Flange for a Liquid Membrane Roof MIFAB series R1200-Z lacquered cast iron extra deep sump roof drain with 20in diameter anchor flange, large cast iron waterproofing membrane clamp ring with integral gravel stop, and standard self-locking polyethylene dome strainer with a free area of 125 square inches.