Measurement method Angle measurement: 1. Adjust the position of the main ruler and the auxiliary ruler to a measurement angle (any angle within the range of 0°~225°), press the ON/OFF/ZERO button short so as to reset the ruler. 2. Use the top surface of the main ruler and the bottom edge of the auxiliary ruler to measure another angle (0°-225°) Horizontal and vertical measurement: 1. The measurement method of horizontal bubbles:   Button Function   ON/OFF/ZERO button: In the power-on state, short press has the function of reseting. Long press has the function of shutting down. In the shut-down state, short press has the function of turning on. HOLD button: press shortly so as to lock and unlock. MODE button: press shortly so as to switch between ° and ′.   Technical Data   Characteristic Function   1. This product adopts high-strength aluminum alloy to the ruler body, which is durable. 2. This product uses a high-definition LCD screen with backlight 3. This product has the automatic shutdown function after three minutes of no response. 4. This product is mainly used in construction, woodworking, machine work, home DIY, etc. Note: The parcel will be sent without battery ,The battery type is 2 pieces AAA battery Color : black or sliver for choose