The David White SLL2 self-leveling crossline laser projects bright level and plumb chalklines for instant and accurate reference marks. Features a magnetically dampened compensator with a self-leveling range of 3.5deg . When the unit goes out of level or position, the SLL2s chalklines will blink to let you know if out of leveling range. Comes complete with crossline laser, wall/tripod mount, laser pole, graduated circle, case and batteries.