The product is easy to use. I set my limit one psi lower than the tire just in case the gauge didn't work. At first I was confused, the testimonies spoke of the border, but they did not turn it off. But I continued on the 2nd try and it got disconnected. It got quite warm, I deflated 3 tires that were too low. But the battery survived. It only took half an hour to fully charge the battery.