I bought this air compressor (used to inflate car tyres) from Pep Boys. In my opinion it is completely unsatisfactory in several respects. Firstly, the pressure gauge on the device is more than useless. It's not even remotely accurate. When my good gauge read 25psi, the Masterflow block read 50-60psi. Very close! Second (and this is the most critical issue for me) it doesn't have an on/off button. The manual says there is an on/off switch, but there isn't one. You "turn" the device on by…