Zircon StudSensor Pro SL-AC Deep-Scanning Stud Finder with How-To Guide Locates the edges of wood or metal studs up to 1-1/2-Inch (38 mm) deep Easy-to-read LCD screen, audio tone and the patented SpotLite Pointing System indicate stud edges Wire Warning detection indicates the presence of live, unshielded electrical wiring up to 2-Inch (51 mm) deep Should scanning begin over a stud, Zircon's patented "over-the-stud" indicator alerts the user to start the scan in a new location Have questions? Need more information? Call the Zircon Customer Service department at 1-800-245-9265, Monday-Friday 9am - 5pm PST. We'll be happy to help!