The ProFlex 790 low-headloss, in-line, rubber duckbill check valve from Proco Products allows for a passive flow and enables the valve to be installed without having to do any modifications to existing structures or preinstall planning. The foldaway design of the inner sleeve allows for a near full port flow, allowing for quick drainage. It provides rapid dispersion of head pressures, and with its low cracking pressure, it prevents upstream flooding. Its zero backflow design makes it a fit for combined sewer overflows, sanitary sewer overflows and outfalls. 800-344-3246; www.procoproducts.com.