Digital Level LCD Inclinometer Protractor Portable Angle Finder Gauge with Magnet Item Type: Level Angle Meter Material: ABS+Aluminum Alloy Weight: Approx. 77g / 2.7oz Product Size: Approx. 5.6x5.4x2.5cm / 2.2x2.1x1.0in Battery Information: 2PCS AAA Battery (Battery Not Included) Measuring Angle Range: 4 x 90° Accuracy: ±0.2° Resolution: 0.1° Display: LCD Display Glows Working Temperature: 0℃- +40℃ (32-104℉) How e: 1. Press and hold the shell by hand in the off state, first press the ZERO button, and then press the ON/OFF button, the LCD displays CAL 0, and it enters the calibration state 2. Release 2 buttons Place the base level of inclinometer on the adjusted level; when the inclinometer is stable, CAL 1 will be displayed. At this time, rotate the inclinometer 90 degrees clockwise and place it on the horizontal surface, a few seconds later, will display CAL 2. Pick it up again and rotate it 90 degrees clockwise, the same as below, until CAL 3 is displayed and it will automatically shut down after it is stable, and the calibration is complete.