This was a great gauge until it stopped reading pressure correctly. I ended up driving 500+ miles with low tire pressure because I trusted the sensor more than what my truck tire pressure monitoring system was telling me. I thought something was wrong with my TPM (tire pressure monitor) in my car. I pulled into a gas station to check my tire pressure and it was 10psi less than the gauge said. I opened up the gauge and noticed that there are 2 gears that are used to set the needle position. I was able to correct the reading by manually rotating the needle, which caused the gears to snap into place. What seems to have happened (at least what I suspect) is that when I deflated the air on the gauge, the gears skipped, causing it to read the wrong pressure. Since there is a pin that brings the needle to the zero position, you won't know this happened if the gear jumps in one direction. In my case, the gear slipped in the direction that caused the gauge to read 10psi when it should have read 0psi (after releasing the pressure with the knob). This is a fundamental design flaw. There must be a way to prevent the gears from skipping. Releasing the air pressure in the gauge can cause the gears to slip. Needs to be redesigned. I'm thankful I didn't get hit driving 500+ miles at highway speeds with low tire pressure (think Ford Explorer). You should periodically check this meter with another meter to ensure it is still reading correctly. I hope this helps and prevents others from driving with over or under-inflated tires. See photos of the gears inside the sensor.