got 2 of these last Christmas, gave them as gifts, both came back in Feb. I tried both on several Presta and Schrader valves, neither was trustworthy. If you knew approx what the pressure was, you could pick one of the multiple different readings presented by these little hummers. IMHO, the ones I got were worthless.
I picked up one of these when I got a fat bike. It gives air pressure in 0.5 psi increments starting at 0 psi which it good to for the low pressure fat tires. I use it every ride. It beeps when it has registered the air pressure which is a nice feature.
I have two primary gripes. One is that in some combinations of lighting and positioning the display is not readable. I may have to rotate the wheel around and adjust my head to see the numbers. Second is I sometimes find I'm in the wrong mode (bar vs. psi). It has a one-button control which is both on-off and mode switch. This plus being hard to see means I do some extra pumping and deflating some days.
The first few times of use, the Airchecker worked ok. The display was not quite showing all the digits, but a tap on it brought them back to life. After a week, the missing digits would not come back to life, and the readout was undecipherable. I am returning the defective item.
I'm running tubeless tires and lowering air pressures so I wanted a precise air gauge to keep track of the pressures I start the ride with. This SKS airchecker digital is the ticket.
I needed something that worked with my new Mukluk to measure low tire pressures and this fit the bill. The beeper is pretty weak and the reduction button doesn't seem to do anything, but maybe that's a low pressure thing. It's usable.