Bosch GLL 2 Self-Correcting Cross Line Laser Level with Mounting Device (AA Batteries Included) Horizontal and vertical line modes - projects two lines independently or together for a wide array of level and/or alignment applications One button operation makes it easy select between horizontal, vertical, and cross line modes or turn the tool on/off Flexible mounting device conveniently clamps to multiple surfaces for quick and easy setup Smart pendulum leveling system - self-levels, senses and indicates out-of level condition; switch slider to lock for transport Class II laser product, 1mW power output