10ARMO 3DMEASUREMENT FOUNDATIONTo check levelChoose a wall and set laser 5M away from the wall. Turn on the laser and cross laser line is marked A on the wall.Findanother point M on the horizontal line, the distance is around 2.5m. Swivel the laser, and another cross point of crosslaser line is marked B. Please note the distance of B to A should be 5m.Measure the distance between M to cross laser lune, if the difference is over 3mm, the laser is out of calibration, pleasecontact with seller to calibrate the laser.mm