... ,Material:rubber,steel 4,12 years OEM manafacturer experience Duckbill Valve,adjustable check valve,rubber duckbill valve1: Product Introduction 1:Rubber check ... opened ,and the higher the water flow is.4:During the back stop operation,the valve will vclose naturally,seal and stop ... ,water conservancy and seawage process so as to prevent reverse flow and reflux,it is an ideal product to replace flat ...