With its slim profile, the Stanley Stud Sensor is capable of detecting wood and metal studs up to 1-1/2 inches below the surface. You can expect accuracy every time thanks to its centre marking channel and auto-calibration. It indicates what it is sensing below the surface with sequential LEDs and audible beeps and is best suited to locating live wire or studs when hanging pictures or mounting a television. Powered by 2 x AAA Batteries which come included.