Whale - In-Line Check Valve - Stepped Connection - 1" & 1-1/2" - LV1215. All Whale bilge switches, non-return valves, strainers and pipework fittings are designed and manufacturers with highest quality at heart. Combine these accessories with your whale bilge pump for a robust bilge system tailored to your vessel.. LV1215 In-line Check Valve 25mm / 38mm (1"/ 1 1/2") Stepped Connection. WARNING: This product can expose you to chemicals which are known to the State of California to cause cancer, birth defects or other reproductive harm. For more information go to P65Warnings.ca.gov.