1-1/2 in. MIP Hydrostatic Relief Valve, Spring LoadedFor concrete or vinyl/fiberglass pools, Hayward NSF listed suction outlets are available in a wide range of styles and sizes to satisfy any installation requirement. Whether you install frame and cover or sump-type outlets for residential and commercial pools, Hayward suction outlets set the standard in quality and value.Hayward WG Series suction outlet assembles are VGB compliant and are tested to ASME/ANSI A112.19.8a 2008 standards.