This 18″ Digital Protractor enables you to precisely set angles in 0.5 degree increments. It has strong magnets on all four edge surfaces and a front locking lever to hold the arm in position while transferring measurements. FEATURES A “HOLD” FUNCTION THAT ENSURES YOU WILL NEVER LOSE YOUR READING, NOR DO YOU NEED TO BE CONCERNED ABOUT OVER-TIGHTENING THE TOOL! Also features a reverse reading capability for those hard to calculate angles. Set miter saws, band saws, drill presses; measure frames, wall angles for cutting crown molding and trim. Packaged with extra battery.