1 Sided Red Beam LaserDetector With Clamp Quickly & Accurately Locates Any Laser Signal Emitted From Rotary Lasers, Includes Clamp For Attaching To Leveling Staffs Or Grade Rods, Audible & Visual Indicators For Precise Leveling, Front Display Is Back Lit, 393.7' Range, 120M Radius, Automatic Shut Off Timer, Dust & Water Resistant.