Digital Goniometer] A perforated digital goniometer to hang a digital angle level, designed for industrial applications that involve setting precise angles, such as alcoves and booths, sloping roofs and handrails (note : it is not a digital level). Backlit LCD displayBacklit LED display, can read data clearly even in low light conditions. High AccuracyMeasurement accuracy 0.5, increase/decrease angle: 0.1, angle range 0-225, allowing you to measure with precision the angle horizontally and vertically. Mechanical LockThere is a LOCK button to keep the angle unchanged during the line process, and a HOLD button to lock angle. Auto Shut-Off It is powered by a 9-volt battery, which is included, and automatically shuts off after 5 minutes of inactivity to extend the duration battery life. ATTENTION: Do not move screws and components haphazardly. Handle your angle indicator with pr&s; caution, use steady force to rotate the rotating arm, and do not use too much force. backlight open too long. When the low power alarm icon appears display, please change the batteries.