I've just bought a RING cordless inflator which looks very much like the one you mention. But if anyone has a RING please post instructions as the pamphlet is very vague. It likes to keep flashing and turning off too soon, so it doesn't even start sometimes. Maybe it's faulty but really difficult to know.
I’ve just bought one of the Ring devices, but until I saw Hugh’s post I hadn’t actually tried it. Have now done so, and it worked exactly as expected. Connect the hose, long-push the on/off button until the display settles, set the desired pressure, push the on/off button again, and wait. Pressure afterwards agrees with my RaceX gauge. I didn’t have any problems losing pressure when unscrewing the connector, so concerns about that are Ill-founded. If I had to be picky:
1. Battery was completely dead when it arrived, it wouldn’t even turn on and required several hours of charging before I got the steady green indication.
2. Battery had dropped from green to amber after checking all four tyres.
3. I wonder how well it’ll retain charge sitting in a cold boot? Only time will tell.
4. Quite noisy when pumping, but I guess they all are.
5. Instructions for the memory function are a bit opaque and I can’t quite figure that out. But that’s no great loss.