Amazon.com Product Description
Designed for professional use, the DeWalt DW071K Heavy Duty Rotary Laser's manual leveling system is accurate to +/-1/4 inches per 100 feet. The rotary laser features dual side-by-side laser diodes for an extremely bright, visible beam, and variable speeds (0-to-600 RPM) for increased visibility. Other features include a protected rotary head and side impact roll cage for increased durability, a built-in bump sensor that alerts you if the laser has been bumped after leveling. This laser can be oriented level or plumb for all common applications. This rotary laser comes with a laser target card and a heavy-duty kit box.
From the Manufacturer
DEWALT DW071K Heavy-Duty Rotary Laser Kit