The twin disc check valve is grooved end style. Grooved silent check valves may be installed in horizontal positions (or vertical with flow moving up). This valve is listed by Underwriters Laboratories of the US and Canada (UL/ULC) and FM Approved. Please refer to NIBCO technical data sheets, chemical resistance guides and catalogs for engineering and installation information. Choose NIBCO® check valves, for the most specified, versatile and economical valve option in commercial, mechanical,more fire protection and industrial applications. NIBCO® check valves are backed by the NIBCO 5-year 125% limited warranty. less