4 in 1 FunctionDigital Protractor Angle Ruler , Spirit Level Ruler (Two level bubbles on the left and right, measure the level of a line), Plane Level Bubble (the level bubble in the middle, measure the level of a plane), Straight Ruler. Horizontal, Vertical, Circular Bubble Level Measuring.7 Inch Digital Protractor Level RulerMeasure angle with accuracy of 0.5, resolution: 0.05 (3), Measure from 0-999.9, Delicate Design and Modern Appearance Digital Angle Finder Protractor is a good choice for family DIY projects, woodworking, decoration, machining.Data HoldDisplay has a hold function to freeze movement for accuracy.If you want to use data holding function, you need to press the HOLD button in red rather than twist the knob. (The knob is just for loosening and tightening. It cant hold the angle firm completely)Large LCD displayThis protractor angle finder designed with full screen large LCD display, easy operation with only three press-buttons, easy to measure and easy to read. (NOTE: It is NOT a digital level. Will not display a number on LCD, just only assist you to judge If It Is Horizontal / Vertical or Not)Power SupplyCR2032 3V lithium battery power supply, large capacity standby with automatic power-off function, This digital goniometer can work more than 2000 hours, saving power consumption and extending battery life.