Updated review after I've had more time with it. Downgrading to 1 star can hardly be used to just blindly download and constantly check with another sensor. This thing gets worse the more you use it. This shows its overall cheapness in design and lack of quality control. The pressure gauge is non-linear, which means that the higher the pressure, the less accurate it becomes. At 60psi, which is the same as many compact spares, the discount is 25%. Yes, you have to set it at 75 psi to get 60. Also, if you hook it up to a tire with more than 50psi, it will overload and shut down, it just can't start reliably. After inflating 3-4 regular tires to 32psi, the unit will get very hot and begin to severely affect the accuracy of the onboard pressure gauge. It no longer has a fixed displacement, but instead jumps by 10psi or more, rendering it completely unusable. You can leave it on the bus without the pump running and the sensor will change on its own. Initial review: Works well but there are a few issues: 1. The accuracy of the meter is terrible, around 2psi. It will show the set pressure but when it stops it will drop about 2psi and never inflate to the set pressure. Setting it 2psi above your desired pressure will leave you stumped, but you still need to check with a pressure gauge and adjust. That kind of defeat put it and forgot it.2. The lettering on the buttons is illegible, not painted over, the buttons are small, it is not clear what the functions of the buttons are.3. As usual with cheap products, the inner tube is pathetically short, with 20-inch tires the pump hangs from the tire instead of lying flat on the ground. The 20 inch is a normal truck tire.