The Stanley Intelli Tools Stud Sensor 200 uses OnePass centre-find technology to locate the centre of studs, joists or live AC wires through drywall or other common building materials.Once the centre of a stud has been detected in one pass across the surface, the Stud Sensor 200 gives a visual display, and sounds an audible tone. A V-shaped marking channel allows easy marking of the stud centre and its edges.The Stud Sensor 200 has an LCD screen and its ergonomic design and soft grips provide comfortable use.Recommended for the following applications overhead lighting, panelling, kitchen installation, bathroom installation, shelving, cabinets and interior decorating. Detection depth:Wood and metal stud: Up to 19mm (3/4in).AC detection: Up to 50mm (2in). Specification: Power: 1 x 9V Battery (not supplied).