It is accurate. That works for me.

Came complete with (dead) battery

I purchased this digital level specifically because it can be calibrated and that it is compact for travel. A lot of digital levels available can only be zeroed which is not the same as calibrating it. Zeroing it has the display set to 0 so you can measure the change in degrees from the starting point. Calibrating it has the display read the same value whether the level is set in one position or spun around 180 degrees to the opposite position. We have a few digital levels at my work that has only the zero function and not a calibration function. I never use those levels as they are inaccurate and when placed on a surface known to be exactly level (0 degrees), they're 0.2 to 0.3 degrees off. We also have two of the M-D Tools 24 levels which use the same module as this one and they're the only levels I use.