Zircon StudSensor 70 Center Finding Stud Finder with Live AC WireWarning Detection and Built-In Erasable Wall Marker The Zircon SS 70 electronic stud scanner detects the edges and center of wood and metal studs and alerts you of live AC wires helping you easily find studs and avoid hazards StudScan mode locates the edges of wood or metal studs up to 0.75 inches (19 mm) deep; DeepScan mode locates targets up to 1.5 inches (38 mm) deep; WireWarning Detection indicates the presence of live, unshielded electrical AC wiring while scanning in StudScan and DeepScan modes ACT (Auto Correcting Technology) automatically corrects common user errors, such as when scanning begins over a stud, in both StudScan and DeepScan modes "Ready" LED lights to indicate when the stud finder is calibrated and ready for use while the patented SpotLite Pointing System illuminates and the audio tone signal sounds when the stud center is located Integrated erasable wall marker enables users to mark targets with the simple push of a button