Simple and effective. Seems accurate. Please note that tire pressure is only sent 2 or 3 times per minute to save energy, so there will be a slight delay. Some reviewers seem to think this is a bug - it's actually fairly common for this purpose and the battery lasts a lot longer. Some points: - You must have the app running and running on your phone for the alarm to sound. It doesn't have to be on screen, but it should work. There's no 'voice', although the app speaks with a voice - it just beeps very loudly when a tire is out of range. - The lower range limit is 17 to 29 psi - below this a signal is output. - The upper range limit is 29 to 58psi - above this it gives a signal 60 to 80Β°C - above this an alarm goes off - As others say you can change the pressure units but the temperature can only be set in degrees Celsius. I don't really think it matters much, but just FYI.