Johnson Level & Tool 40-6536 Electronic Self Leveling Horizontal Rotary Laser System Designed for outdoor use and simple set up, Electronically-controlled dual slope feature Electronic self-leveling in the horizontal plane, Visual and audible alarms when beyond leveling range Single speed rotation 700 RPM, Slope operation function allows user to perform slope 8 degrees in both x and y axis Remote control and detector for one person operation, Height of Instrument/Tilt alarm function ensures product accuracy Laser Class Illa, &lt;5mW