Project highly visible horizontal and vertical laser lines together, or either one independently, with the BOSCHÂ Self-Leveling Cross-Line Laser. This Bosch GLL2 laser requires only 2 AA batteries to work, and includes a pair to get you started. Its alignment projection lines extend up to 30 feet, and a one-button switch powers the device on and off and selects the vertical, horizontal and cross-line projections. The Bosch cross-line laser has a smart, pendulum-drive self-leveling system that senses and indicates when structure is out of alignment, up to 4 degrees. This self-leveling laser is mounted to a fine-adjustment friction arm with a 1/4-20 thread, and the mounting has a spring clip that clamps it to almost any interior surface.