Daldorado DALMAX-SG-183624-FA08-40 Dalmax™ 18" x 36" x 24" Fiberglass Sump & Grate with 8" SCH40 Female Adapter DalMAX™ main drain sumps for commercial pools are constructed of reinforced fiberglass with frame and grates made from the highest quality PVC materials tested to ANSI/NSF/CAN 50 2020 and are tested and certified as a SOFA to ANSI/APSP/ICC 16-2017. With a large open area of 62%, DalMAX™ is the clear choice for every new commercial pool construction or large area main drain replacement (frame and grate).