awesome.
turn on, set the pressure value, press start and tire will inflate to that pressure and stop.
swappable batteries is important. Some large tires will drain a small battery and you can switch in a new one.
The ones that plug in to a lighter socket (which sometimes require the car to be running or the ignition switch in ACC position), or have to be clipped to the car battery are not as convenient.
I bought a series from Slime brand; every one failed within two tire inflates. Went to Harbor Freight, and bought their most expensive one; it has earned the price since (still under $100).
It's saved my butt many times.
Mine is viaair, and the device is dedicated (no flashlight etc)