Review on DigiPas DWL80PRO: Compact Digital Level & Angle Gauge - Accurate Protractor, Bevel Gauge, and Angle Finder, 0.05° Sensitivity, 4 inch Pocket Size by Antonio Taveras

Great multimeter, but no matter what you calibrate, Y will adjust to 90 degrees, even when it actually is it 45 degrees. You must first set the X perfectly and calibrate the Y to true 90 degrees using the quality square so that the level is set perfectly. Remember which direction the level was pointing (orientation) when you calibrated it in X and the same way when you calibrated it in Y, and take all measurements with the level in the same orientation. If you do, you will enjoy this level. If not, you will hate it. I learned this the hard way.