Dewalt Laser Plumb Bob - Self-Leveling Plumb Bob Is Accurate To ±1/8" @ 50' - One Button Operation Is Fast And Easy To Use - Overmolded Housing Helps Maintain Calibration Under Jobsite Conditions - Focused Laser Beam Keeps Dot Small Even Over Long Distances For Improved Accuracy And Visibility - Locating Magnets Hold Laser To Metal Track For Easy Positioning - Cross-Hair Beam Pattern Helps User Find Center Of Beam