feature:High precision 0.05, high resolution 0.01. Lithium-ion battery is rechargeable and durable. High resolution, professional measurement. Single and double axis, convenient angle measurement. Dual axis and single axis with user friendly LCD display angle. V-shaped housing for easy installation in corners or pipes. With a 7-sided magnetic base, you can set audible alarms within the angle range, any angle measurement. The unit can be charged by connecting a USB cable to the unit and the USB port of the computer.With this axis digital protractor, you can measure the angle between two faces, not just the direction of Earth's gravity. Press the angle key on the first face, then rotate slowly, you have to keep the rotation axis pointing to the other test face, once you don't move the unit, it will show the angle. Any angle measurement uses gyroscopic technology.