Litoexpe 1/2" One Way Inline Check Valve, Non Return Ozone Resistance PVDF Plastic One-Way Fuel Oil Water Gas Pump Air Check Valve, Pack of 2

These check valve work quite well. I have not experienced any backflow issues since installing them.

I purchased these check valves for use in my counter mounted soap dispenser line. My soap dispenser uses a tube that feeds from a bulk soap bottle located in the cabinet below the sink. My original set up used a check valve that clogged after the metal in the previous valve corroded. I do not know if this valve uses a metal to activate the valve, but time will tell if it corrodes. Have used a month and soap is flowing. I did have a terrible time inserting it into the silicon line. I would suggest selecting the next smaller size check valve OD diameter based on the ID of the tubing you plan to insert it into.

I used these check valves for some pontoon vent hoses. I fabricated a pontoon pumping system and these check valves allow air to enter the pontoon when the pump is on. The whole system works great. You can see it in the pictures at the tops of the clear hoses.

Saved me from buying new condensate pump!

Bought two of these about ten months ago. Each one failed. The second time, the failure resulted in a back siphon in my aquarium, and I ended up with a couple of gallons of water on my living room floor.