QWORK 2Pcs Brass One-way Check Valve, 1/2" Female to 1/2" Male Thread of Backflow Preventer

It works perfectly. Cold water was mixing into the hot at one of my sinks. This isolated them and my problem is gone. If you need a backflow valve, this one works!

Arrived timely good quality

I installed this inline in my RV water system. It immediately reduced water flow and pressure. I don't think the shower would be at all effective. After 2 weeks it clogged up. My freshwater tank was cleaned in early spring, so there is probably some growth over the summer, but the water smells and tastes fine and has no slippery feel. I installed the second one while I search for a better solution. I put fresh water in the tank before installing the 2nd one. It stopped flowing today. I took it apart and found they are not clogging up, but getting stuck closed. THEY ARE NOT SUITABLE FOR RV WATER SYSTEMS! Also note that the threads are not NPT. They will fit NPT, but you will need to use thread tape.

They work perfect Add some loctite 567 to the threads and you're good to go

Fit well at all connections, no leaks. Seems to control flow well.

M.I.P. threads cut wrong on both units. Had to send back.

no surprises with incorrect threads and works for what I have intended for it in a nice compact package(using it in a DIY vapor blaster setup)

This part worked great for me after getting an adapter for the correct threading. I used this part under high pressure compressed air and so far it has held up against 150 psi. I turned an old broken compressor into an inline auxiliary air tank/portable air tank. Would have given 5 stars if it had stated that the threads are not standard US NPT threads. The threads are NPS threads which are straight while NPS threads are tapered. Good product though

Works as described. Easy to install. Used these to fix a shower cartridge that was leaking hot water through to the cold water system. I didn't want to replace the whole fixture, so I installed these in the supply lines and it fixed the problem.

Used these to fix a shower cartridge that was leaking cold water through to the hot water system. The cartridge was unusual and I didn't want to replace the whole fixture, so I installed these in the supply lines and it fixed the problem.

had a problem with water reversing in piped waterline. These one way valves fixed it immediately

very little volume of water, not enough to support rv water system,

Used it to fix my RV water pump it stopped filling my my fresh water