Features: 1. Put the machine on a level surface and boot. The surface is in level condition when the bubble is in the center of the crosshair. 2. If tilt angle of the machine is greater than 3.5 degrees, the projection line would prompt in the form of flashing. 3. When the light the machine emitted is dimmed, that means too low battery and you need to replace the battery. 4. Small volume and light weight provide great portability. 5. Long battery life for a full day of use. 6. 1.2m height resistant to falling. Specification: Model: CR2-RS Laser class: Class 2 Laser wavelength: 635nm Power: 7mw Measuring range: 10m Measuring accuracy: ±3mm/10m Angle measuring range: 3.5 °±1° Self-leveling: <3s Battery type: 2 x 1.5V AA batteries (NOT included) Protection grade: IP54 Storage temperature: -10~50℃ Size: 72*72*72mm / 2.8*2.8*2.8in Package weight: Approx. 294g/10.4oz Package list: 1 * Laser Level 1 * USB Cable 1 * English Manual Note: 1. Due to the difference between monitors and light effects, the pictures may not reflect the actual color of the item. 2. Please allow slight error due to manual measurement. Thanks for your understanding. 1、Put the machine on a level surface and boot. The surface is in level condition when the bubble is in the center of the crosshair. 2、If tilt angle of the machine is greater than 3.5 degrees, the projection line would prompt in the form of flashing. 3、When the light the machine emitted is dimmed, that means too low battery and you need to replace the battery. 4、Small volume and light weight provide great portability. 5、Long battery life for a full day of use.