I did not expect this product to be as good as it is. The current tire pressure is displayed when you attach the pump to the tire. Set the desired pressure and press the power button. The pump will turn itself off when it reaches the desired pressure. Tested accuracy using a standard PSI gauge was only wrong by one PSI, so who knows which gauge was more accurate. A limitation. If you are using PSI as your tire pressure, make sure the pump is set to PSI and not some other standard or you may over inflate your tires.