They work, but it takes awhile to totally cut off the flow. I mostly needed to reduce the flow to one off my lines so it does work well for that purpose.
I needed inline air valves to adjust down the flow from the pump to the air stone on two different tanks where more O2 is probably necessary, but not nearly at full blast. I came on here to buy the little green plastic ones I've always purchased in the past. Well, they're no longer on here, but this looked better for the price.
The construction build is definitely way better, but the valve does not function correctly. The knob is very tight, and it doesn't close all the way. Not a big deal if all I'm doing is making the bubbles chill, but what if I want to turn it off? I do that a lot of times when I'm feeding my beta since he's kind of stupid and can't seem to smell the food to go after, so I don't want it floating away from him quickly. I did buy a third valve for that tank, but I ended up leaving the green plastic one inline since it does shut all the way off.
I see that someone said they used plumber's tape to fix a leak (maybe the same issue), but hell if I know how to do that. I'll have to try. As is, it's a 2. If it shut off all the way and was easier to turn, it'd be a 5.
After using numerous air valves on my central loop air system this has been the easiest to adjust and the most durable. Solid construction, and finally an air valve with a large adjustment knob that is easy to fine tune.
It is an air valve. It does what it is suppose to do. No complains.
They all leak past the adjustment screen. No real big deal. Just used a little plumber's tape and stopped the leak.