Review on 🐠 BornFeel Plastic One Way Non-Return Check Valves 16pcs - Aquarium Air Pump Accessories for Fish Tank by Sarah Brown

Four stars here because we had some issues with some that didn't seem to work. We used them in an aquarium CO2 setup to prevent water from flowing back into the tube during the night and the first pair we used didn't seem to work, but the next few did. So if you find yourself having problems, try changing them a few times until it works.