Review on XMLEI Precision Leveling Instrument: A Reliable Tool for Accurate Household Leveling by Richie Jacobson

Only one side of the four I received is dead and I assume they are all like that. So find something that you know is level or compare it to a level that you know will be read correctly, spread out and turn until you get the right side on each find, and then mark the ground with a marker. You would think they would have done it in a factory. But now you have four mini-levels that you can trust for a good price.