These 15-1/4” (390) diam. drain assemblies are engineered for installation in flat roofs waterproofed using the Insulated Roof Membrane Assembly (IRMA) method. A 4” (100) high perforated stainless steel gravel stop that restricts crushed gravel commonly installed with IRMA roofs from entering drain lines is provided with each drain along with a polyethylene domes (for leaf debris). These Duco coated cast iron drains are available with several flange and clamp configurations for installation in roofs where built-up felt and asphalt waterproofing is installed.