The Stanley STHT77587-0 S1 Stud Sensor detects wood and metal studs up to 19mm below surface materials. With a slim profile design it features auto-calibrating AC detection. The stud finder indicates what it is sensing below the surface with sequential LEDs and audible beeps. This ergonomically designed wood and metal stud finder has a slim profile which makes it comfortable to hold. It's easy to use and works with a single button operation. This tool is designed with auto calibration to accurately indicate the location and direction of studs. This is made easier thanks to easy to read LED lights that work in a sequence and audible beeps that let you mark surfaces easily and accurately.