Allstar Performance digital levels take the guesswork out of reading and calculating angles, grades, and plumb. These compact units can be used to measure the angle of a single straight surface, or the angle of a joint between two straight surfaces. Built-in magnets on each unit's base can attach firmly to many surfaces you need to measure. The backlit LCD screen offers increased visibility, and the displayed readouts rotate to right side up when your level is in an upside down position. Allstar digital levels are available in multiple styles, and use three included 3 V CR2032 batteries as a main power source.