No need to run to the local gas station with quarters and pay for air. I keep it in the trunk (we have a DC outlet in the trunk - a lot of new cars have them). Every 2-3 days I plug it in, check the print and quickly add. The built-in sensor fits my digital sensor perfectly. It's a bit noisy but compact. Light is a nice touch when you need it. I've been using it regularly for about a month and I might buy another one to leave at work in case I'm in a hurry and miss my morning air check before travel!