Offered in 2 and 3 in. dia sizes, SureSeal® Plus consists of waterless in-floor drain trap seal with additional check valve to protect against property-damaging water back-ups. EPDM water-blocking check valve flapper and housing withstand up to 5 ft of head pressure. Besides flood prevention, unit uses waterless trap seal technology to block toxic sewer gas and insects from infiltrating occupied areas. ASSE-1072-compliant design uses built-in ½ in. dia airlock vent to relieve pressure.