rubber check valves 1.sizes:DN25mm~DN5000mm 2.parts:rubber,hoop 3:material:rubber,stainless steel 4:ISO9001,ISO14001 rubber check valves,rubber duckbill valve,rubber expansion check valve flange flexible duckbill check valves made in our company have been constantly receiving ruputation not only home but also abroad. These valves are our special product , and it is used for draining sewage. we ...