This was the second RoadPro unit that I tried, as the first one came to me as a previous return from another customer. Now I know why it was returned....don't waste your hard earned money on this piece of junk! Although the temperature part of this unit seemed to work fine, I was never able to get a calibration on the compass. tried several times, tried replacement battery, tried different mount positions, IT WOULD NOT WORK! I ended up going "old school" with a mechanical "bubble type" compass.