Black & Decker, All In 1, Laser Level, Mark Free Technology Holds Securely For Up To 2 Hours Without Leaving A Mark On Your Wall, Visual Level Indicator Automatically Changes Bubble Vial Color From Red, Not Level, To Green, Level, Audio Signal Aids In Accurate Leveling When Out Of Sight, Magnetic Attachment Allows You To Flip Unit To Project Laser Line To The Left Or Right, Applications Include Hanging Pictures, Leveling & Laying Out Of Shelving, Leveling A Refrigerator & Leveling A Desk Or Piece Of Furniture.