Measure 360 and Hold Data Protractor measuring range 0 999.9 Resolution 0.05(3') Accuracy 0.5 The goniometer, can measure 360inner and outer angles, supports degree and degree minute unit conversion. It has hold button and zero button. To lock the data, please press the HOLD button. (Turning the knob is only for loosening and tightening, can not fully fix the angle 4 in 1 Multifunctional Digital Goniometer This product is a combination of protractor, level to bubble,circular spirit level and ruler.It is calibrated by 3 spirit levels.Help you measure the angle better.(NOTE This is NOT a digital level, there is no number displayed on the LCD display, can only judge whether the object is tilted).The main ruler is double scale in metric and inch. Large LCD display and automatic shutdown This protractor has a large full screen LCD display that allows you to read data easily and quickly The digital angle ruler automatically turns off after 5 minutes of inactivity to save power The digital protractor also has a zero button that can be zeroed at any position and is suitable for absolute and relative measurement. Material of Ha High Quality and Portable Design The thickened and widened ruler body is made of high strength nylon fiberglass construction material, which has good hardness, wear resistance, no deformation, no scratches, lightweight and durable 230mm, small, delicate design, easy to use and carry. Hanging hole design is convenient for hanging.