Stanley 77-250 IntelliSensor Digiscan Wood, Metal and Live Wire Stud Sensor Electronic stud sensor differentiates between wood, metal and live wires through most common wall materials Locates wood studs and live AC wires in both 3- to 4-inch standard and 1-1/2 deep-read modes; automatic calibration Heavy-duty ABS construction; ergonomically designed Audio indication and easy-to-read LCD display for accurate center and edge marking Uses 9-volt battery (not included); backed by limited lifetime warranty