Zircon Pro SL-AC Series 61903 Stud Sensor, 9 V Battery              Locates the edges of wood and metal studs and joists behind walls, floors and ceilings up to a depth of 1-1/2 in. The SpotLite Pointing System shines a beam of light on the wall to identify the target and WireWarning detection indicates live AC voltage. TruCal technology calibrates to any wall's density and a steady green LED light alerts the user when the tool is calibrated and ready to scan. The tough, ergonomic housing withstands everyday jobsite use.