Take the guesswork from measuring, marking, reading, and transferring angles with the General Tools 822 Digital Angle Finder Ruler. One button activates the reverse angle function, a hold button digitally saves the measurement, and the large ergonomic locking saves the angle manually. The protractor tool includes a battery-powered gauge with a 1 CR2032 lithium-ion battery. It helps guide you through your wood-inspired projects, stair and patio construction, tiling, and many woodworking, carpentry, and contractor needs in the shop and field. This digital tool combines the ruggedness of analog rulers, both standard and metric, together.