... Duckbill Valve,duckbill valve,slip on duckbill check valveThe rubber Duck-bill check valve is all rubber reinforced. It consists ... back stop,no leakage,back flow prevention,the higher the back pressure is ,the better the effect is.4, Corrosion protection,aging protection,no deformation ... )Certificates obtained:Rubber Duckbill Valve,duckbill valve,slip on duckbill check valve For Sewage Treatment slip ...