Hi,
I have one of these, I originally purchased this a couple of years ago to use on my Land Rover Defender. It has proved very efficient and reliable and can inflate the tyres on the Land Rover very quickly, much more so than one of the cheap tyre inflators sold in plastic cases by most DIY stores and Motor accessories dealers. It is solidly made of metal construction. You will find that it can inflate a caravan tyre within a couple of minutes, pressure adjustments +/- a few psi take seconds. As for accuracy, difficult to judge, unless you have a calibrated standard to compare it to, I suppose you could take your vehicle to a garage and compare their gauges with the T-Max gauge, but who's to say how accurate their gauges are?
If you do get one I don't think you'll be disappointed.
Chris