Astro Al will turn itself off when you weigh 1.5 pounds. higher than the set pressure. This compensates for the air that can escape when the tire valve is pulled off. Plugging in is no problem. The question is where is the valve when you go to inflate it. The automatic shut-off relieves the user of having to look after the pump while it inflates the tire. The screen is big enough. From what I understand Astro Al uses a Vain pump so the amount of air it produces is small but it has the ability to produce high pressure. However, with an automatic switch-off