Feelers 1/2" (12MM) One Way Inline Check Valve Non-Return One-Way Air Water Gas Check Valve Ozone Resistance PVDF, Pack of 2 2PCS

The price is really good for the amount of them you receive but the the quality definitely shows for the price you pay. So if you want something more durable I recommend spending a few more but if you looking for a quick fix and quantity then this I definitely recommend:)

Using on my cooling system for my CNC machine. I put it at the discharge of the pump so that when it is shut off the cooling lines don’t empty out.

Don't expect to get 1/4" plastic tubing on these. They will fit silicone tubing, but not anything that is stiffer. They also required far more pressure to open the valve than I expected. I can't really use them very easily in my application.

While the seller states that these valves are ozone resistant, they are not. They fail within a few months exposure to the ozone output with the connectors cracking and breaking off causing failure in the water treatment.

Not able to use in my hot-tub ozone intake. The suction needed to overcome the spring force of this directional valve was more than my system could provide. This valve wouldn’t allow ozonated air to pass.My spa uses a small 1/5 hp circulation pump that has very little suction. This one-way valve would not flow. It took all my breath to operate this valve.Valve appears to be good quality. Just not good for my application. I kept the valves but if I had know there suction requirements, I would not have purchased them.

My first time using these valves. Pay attention to inside diameter of your tubing and then the faint arrows on the valves themselves and they work like a charm.

Installed with arrow towards engine fuel pump. Fuel did not flow as needed. Had to remove and replace with old valve.

I used this for soap dispensing. It only lasted a year.

Fait le travail.