The DW077 is another classic, reliable rotary laser from Dewalt, the maker of so many different types of construction and DIY equipment all over the world. The DW077 is a remote control operated laser level that finds the correct horizontal level, automatically. Just mount the device on a good surface, or use the supplied bracket or optional tripod and you are good to go. The DW077 laser level can send a beam out over distance of up to 200ft indoors and 2000ft outdoors when used with the Dewalt laser detector. It is also accurate to within 1 8th of an inch over a distance of 100ft. A great thing about this rotary laser is that it uses the standard Dewalt batteries, from 9V to 18V.