Using the DeWalt DCLE34021B Cross Line Laser is a breeze. First, mount it on the bracket or tripod using the provided mount. If you're working in a large area, you can use the detector (sold separately) to extend the working range. To turn it on, just press the power button, and it'll remember the last mode you used for a quick start. When taking measurements, make sure the surface is clean and stable. For best results, use the target card to clearly see the laser lines. Keep in mind that the service and storage temperature should be between 39.2 °F to 104 °F (4 °C to 40 °C), and it can work at altitudes up to 6500' (2000m). When not in use, store it in the carrying case to protect it from dust and damage. Regularly check the battery level, and use only 20V MAX batteries up to 5 Ah for optimal performance. Also, clean the laser diodes gently with a soft, dry cloth to maintain good visibility.