The LaserMark LMH Series Automatic Self-Leveling Rotary Lasers offer fast and simple leveling power to handle your toughest indoor/outdoor jobs with less manpower. The LMH Series levels itself via electronic sensors interfaced with motors, eliminating the need for re-leveling or rechecks. No more fussing with manual leveling screws or bubbles; just turn it on and you are ready for work! Plus, the built-in ADS sensor provides peace of mind when working on a busy job site; if the lasers H.I. (height of instrument) is altered due to tripod movement or an accidental bump, the operator is instantly alerted.