This little die grinder is amazingly powerful and smooth. I run it at around 110 psi. from a small 20-gallon 110V compressor and it works beautifully but since the tool consumes between 20 and 34 SCFM I cannot run it continuously for a long period. I have to give the compressor time to catch up every so often. The small size helps it fit into tight spaces and make maneuvering it around a complex work piece much easier.It comes with two collets, the American standard 1/4" size and the metric 6mm (which is slightly smaller that 1/4" by .35mm) so that if you buy the imported burrs and bits they can be securely fastened into the chuck. Other tools I have that are only 1/4" often can't tighten down sufficiently on a 6mm rotary burr shaft. This one works great.The two chuck wrenches that come with it include one that has the smaller jaw at a right angle that allows you to lay it parallel to the tool in use and hold it and the tool in one hand while you tighten the chuck with the other wrench. A genius design.The owner's manual makes no mention of the "built-in regulator" that is part of the tool description. I have included a picture of it. If you turn the inner screw, the tool adjusts its speed accordingly, which is really handy when driving something like a wire brush so it doesn't overspeed and throw wires around. The control is VERY touchy, but effective. I can slow it down to a crawl or up to its maximum 27K RPM with just a little turn of the regulator.The rear air discharge is diffused and out of the way so it doesn't blow chips around but, like every rotary air tool, quite loud, so I strongly suggest some hearing protection for long-term use.A few drops of air tool oil before use and a good supply of clean shop air and it will work for you all day. It is well made, hefty for its little size and quite powerful. The fit and finish are top notch at a very reasonable price.