Very small but conscientiously to use. The screen will show you the exact psi when pumping air to my car. I got 2019 Chevy suburban, there is no problem to pump all four tire from 29 to 35. It took 20 mins. The screen will show you five different type of air pump mode, set up desired pressure then it will automatically stop pumping when it meets the desired pressure. Save the time to monitor the screen.