I carry a spare tyre with my car and don’t have a car tyre pump. I purchased this unit so that I could check and keep my tyres at the correct tyre pressure. It will also come in handy if I need to top up the air and I am in a remote location. You just need to set the tyre pressure from your car manual and start the unit. The compressor will stop when the correct tyre pressure has been reached. The unit also comes in a nice protective zip-up case to keep it safe and clean.