I already had a tire inflator but it was only 12vdc so it only worked when the car engine was running and I was wondering about the drain on my battery, especially now in the pandemic time when I don't drive that much. Since, in my experience, I only inflate tires at home and in the garage, I chose a device that runs on household electricity. Not only does this device work with either power source, but it also has two large buttons to select which source is being used. As with all tire inflators, the PSI gauge is an approximation, and the Kensun was a few pounds below what my more accurate oil pressure gauge indicated (my old tire pump was a few psi more), but I was expecting something similar. My only wish is that the actual PSI sensor on the device is larger, as I am now retired and approaching an age where my eyesight needs extra help.