... ISO9001 and ISO14001 2,DN50~3000mm 3,Material:rubber,steel 4,12 years OEM manufacturer experience Duckbill ... flanged duckbill valve,rubber duckbill valve 1:Basic information:Manufactured with an integral reinforced rubber flange complete with metal backing rings, ... needs. Flat faced, reinforced rubber flanges with metal backing rings are drilled in accordance with customer specifications. In addition to ...