Quickly and easily locates the edges and center of wood and metal studs and joists behind walls, floors, and ceilings. It also locates metal targets up to 3 in (76 mm) deep. A 3-mode switch makes it easy to change functions, while the display screen,SpotLite Pointing System, and audio tone all indicate the location of the target. The signal strength indicator helps to distinguish between shallow and deep targets. ACT (Auto Correcting Technology) automatically corrects common user errors, such as whenscanning begins over a stud. WireWarning detection indicates the presence of live, unshielded electrical wire up to 2 in (51 mm) deep in stud and metal scanning. Requires 9V battery not included.