Cla-Val Pacific Series DBI Duckbill In-Line Flanged Style Check Valves are for pressurized pipeline applications where it is inserted between pipe flanges. Cla-Val Series DBI Duckbill In-Line Flanged Style Check Valves have an integral rubber flange for attaching directly between flanged-end pipe connections. A variety of elastomers allow DBI valves to be used with many fluids. When ordering, specify Model DBI, pipe ID size, flange drilling, and add first letter of elastomer material. IE: 4"-DBI-N (N for Neoprene).