This device actually is less big then it seems. Box models are considerably larger. It starts up in the old but very much used Bar mode, which means I don’t have to change this setting as all my vehicles have the Bar setting too. When attached to the tire, it gives the actual pressure, and when the switch for inflation is put on, it starts inflation up to the setting chosen. Then it shuts off. There is another switch which puts the LED beam on & off. The system is not quiet but more quiet than a box system (I also own). It seems to have 2 cylinders, and all together I like it!