The DW074KD self-leveling interior/exterior rotary laser from DEWALT is not only accurate to plus or minus 1/4 In. per 100 Ft., but it's built to take the bumps of the job site as well. A durable rotary cage helps protect the rotary head when dropped and an innovative configuration of multiple, thin struts maintains the unit's strength while eliminating blind spots. And it's easy to use! The unit is self-leveling in horizontal mode, and the addition of arrow buttons used for manual leveling in vertical mode are far more intuitive than traditional knobs. The beam is bright and sharp--it can be seen up to 100 Ft. indoors and can be detected up to 1000 Ft. in diameter outdoors. The laser also offers a weather resist housing which offers a durable and accurate service. The new DW0742 laser detector and clamp will locate the beam up to 1000 Ft. (diameter) from the laser.