This is a very high quality piece of equipment, and I am very pleased with it, though it does have a couple of peculiarities.
Firstly, the RAC900 is powered by clipping it directly to a car battery. This will not be convenient to everyone, and is not as convenient as a conventional 'cigarette lighter' socket found on most alternatives.
Secondly, the pressure gauge is on the air hose, less than a foot from the tyre valve attachment. The on/off switch is on the unit itself. This means that, as the hose is very long (and therefore convenient), I find myself walking back and forth to turn the pump off, read the gauge, turn it on again, turn it off again, read the gauge etc.
However, as stated initially, this really is a very high quality piece of equipment, and despite its slightly unique design traits, it still comes very highly recommended.