Zircon Studsensor HD35 Stud Finder (2 Packs) Locates the edges of wood or metal studs up to 3/4 in. (19 mm) deep Wire warning detection indicates the presence of live, unshielded electrical wiring up to 2 in. (51 New "Ready" light indicates when calibration has completed successfully Red arrow segments up sequentially as the stud finder nears a target New "Edge" light indicates when the tool is over a stud edge