I bought this compressor as a replacement for my old mini compressor and was immediately impressed by how much better it was and how much easier to use than my old one. Having read the four previous reviews, 2 giving 5 stars and 2 giving 1 star, I can only conclude that two people weren't operating it properly, whilst the other two were as impressed with it as I was. To use the auto shut off facility, you simply set the required pressure using the + and - buttons and flick the switch to Auto. The pressure guage will fluctuate whilst inflation is in progress and then shut off when the desired pressure is reached. I then checked the pressure with another reliable guage and it was spot on. One foot note. The maximum pressure it will inflate to is 100 p.s.i. so I guess that Pro User 250 PSI is just it's name. But no matter, I like this compressor, I like it a lot.