+ It's a laser measure. Way faster and more precise than tape, not affected by thermal expansion or shrinkage, and totally immune to sagging. Stated accuracy of 2mm at 100m is simply incredible. + Unlike many cheap (and not so cheap) laser measures, this one remembers the settings during power cycling, which is a huge plus. + Pressing the \"units\" button instantly converts all of your saved data to the new units. + They've even included a little retroreflective \"target\" card!… I taped mine to the device with a gaffers tape, so I won't lose it. Sticking a magnet to that card could also be a good idea if you're working with iron beams, rebar and such. – The laser is red, making it difficult to use in broad daylight. However, to my pleasant surprise, the \"eye\" of the device is much more sensitive than the human eye, so it's able to \"see\" the laser even if you can't. When \"guesstimating\" for certain projects (for example, fences), I was able to easily read distances by \"shooting blind\" at wood and concrete from a few hundred feet away in blazing Georgia sun. Maybe I'll add a red dot sight to this thing eventually to help with the aiming. – This is common across all laser measures, no matter how cheap or expensive… Some fancy \"Pythagorean\" calculations are imprecise. While the laser is a very good tool to measure distance, its built-in clinometer sensor is not very good. So take any measurement that needs an inclination reading with a grain of salt and only use it as an estimate. + \"Pythagorean\" calculations that do not need angular measurements are, of course, very precise. PS: Vevor, if you're reading this… Add a picatinny rail to the side of your next generation laser, so we can put a small red dot sight or even a scope on it. I'm not even kidding, the device has a perfect thickness to add a pic rail!