very easy to use. i purchased the AEV procal a day after i got my wheels/tires.
the display lights were bothering me as well... and having to guesstimate the actual speed on my speedometer.
with the procal, i turned off the tire sensors, and corrected my speedometer. Pretty easy to use. just do the settings for ur tires, plug it in and wait for the horn for confirmation, then repeat for ur other calibrations.
since i recently got a flat and didn't notice until the next day (my tires are SUPER QUIET even when flat) i activated my sensors again.