Inaccurate, far from it. The purpose of the level is to find the level or deviation from it. These units are basically useless as far as it goes. The dragonflies are "off" on all the ones I've ordered so far. But that's not the case. One way is to show the level (or some degree of misalignment) and if you rotate the level 180 degrees you won't get the same reading. See photo. The 2nd photo is rotated 180 degrees. This is the 2nd and 3rd block I have received. send her back There is no possibility of adjustment (no disassembly and probably extensive rework). Bad quality control. I'm wondering how many I have to order and return before I find a good one.