Using the Bosch GTL2 Laser Level and Squaring Tool is a breeze. First, take the laser level out of the package. Use the adhesive mounting strips to attach the unit to a smooth surface where you need to work. Press the easy - to - press push button firmly to make sure it's securely in place. To start, just press the one - button operation to turn on the two perpendicular laser lines. You can then use the alignment guide to set your layout at a 90 - degree angle or adjust it in 5 - degree increments as needed. When using, keep in mind that the maximum working distance is 30 feet, and the accuracy is 1/2 - inch at this distance. Don't use it in extremely bright environments as it may affect the visibility of the laser lines. For maintenance, when the AA batteries run out, replace them with new ones. Also, keep the unit clean and dry, and avoid scratching the laser diode. If you have any other questions, feel free to check the product manual.