I bought this a few weeks ago from Get A Gauge.com. I've used it a couple times now and it works well. It will take one of my 33's from 33 psi to 15 in less than a minute. Much faster than my old method of using the back of a pencil gauge.
This deflator works by removing the valve core from the stem. You just screw the end on to the stem, turn the core remover counter clockwise a few times, and pull it back. The air begins to rush out. To check the pressure, push the core remover back in and read the gauge. Once you reach the desired pressure, turn the core remover clockwise a few times to reinstall the core, then unscrew the gauge from the stem. Not a bad purschase for $30, which is bit less than the Staunn deflators.
I'll post of review of a very affordable 12v compressor I bought once I've had time to test it well.
-Michael
p.s. Good idea on the Product Review section guys.