Easy to use right out of the box. Connected to car DC socket. By default, the compressor is set at 30psi. Pressed + to 35 psi. I put the nozzle on the tire bar and fixed it. Turned on the car and returned to the air conditioned car. The compressor will automatically shut off once the desired psi is reached. This increases the leakage by 0.5 to 35.5 (I think). The car computer showed all tires at 37 after inflating each tire to a 35.2 pound difference. You can either fix it or leave it alone. To be honest, tire pressure changes daily in Florida. Note: The compressor's nylon tube gets a little warm, as does the car (90 degree weather didn't help). Overall: This is a small, solid machine. Highly recommended by a person who mainly works from their car.