Description: With 3 built-in magnets in measuring surface, which is convenient to be attached to the object measuring workpiece. Use 1 pieces of CR2032 button cell, low power consumption makes it durable. Made of plastic, light weight is convenient for you to carry it wherever you are. Portable size, convenient to with other measuring tools and enlarge measuring range. High accuracy makes work much easier and accurate. Specification: Metarial: Plastic Size: Approx. 55x55x16mm / 2.17x2.17x0.63inch Measuring range: 360 Degree Accuracy: 0.1 Degree Battery: 3V, 1 Piece of CR2032 Button Cell(included) Working temperature: 0 -40 Degree Absolute zero measurement based on the horizontal surface Operating Instructions: 1. Press the "ON/OFF" button for three seconds, it turns on, and the LCD displays absolute horizontal angle. Press "ON/OFF"button for three seconds again, it turn off. 2. Press the "Calibrate" button, the machine will return to zero, the value returns to zero, and the read-out is the angle value measured angle value relatively to the horizontal stand. 3. Press the "Unit" button, you can change the degree unit into percentage unit. 4. Press the "HOLD" button, the value on the screen will be locked. 5. The magnets at the bottom allow the instrument to be attached onto iron material measurement object. Press the "Calibrate" button reset the value to proceed relative measurement. Package Includes: 1 Piece of Digital Protractor Note: Please allow 1-3mm error due to hand test