By being able to measure the vertical plane, horizontal. Or even a 45 degree angle. Featured: 1) The three models at the same level. Including horizontal, vertical and inclined at 45 degrees. 2) Sound a warning when it finds that the measure in the horizontal plane. That is the angle measured in the plane is less than 1 degree (you can enable / disable this). 3) While the display is illuminated at all times, making the work easier (you can enable / disable this).