StudSensor Pro55 SL LCD finds wood and metal studs and joists behind walls, floors, and ceilings up to 1-1/2" (38 mm) deep and indicates the presence of hot wires. Locates standard household 120 VAC wiring. Finds both wood and metal studs, select between 3/4" scan depth and patented 1-1/2" DeepScan mode. Patented SpotLite Pointing System, audio signal, and LEDs (light emitting diode) indicate stud edges. Nonmarring wall pads. Continuously detects and warns of hot AC wires, detects the presence of unshielded, hot AC (alternating current) wires in all modes for safety. Finds wires in plastic conduit or Romex cable. Easy to read LCD (liquid crystal display) screen.