The Black and Decker BDS300 Detector is a multi-sensor for wood, metal pipe and AC live wire detection. It is ideal as a precautionary measure prior to drilling. The detector has continuous AC wire warning and visual and audio alerts. Depth of detection: Wooden studs: 19mm. Metal studs: 50mm. Copper pipes: 25mm. AC wire: 50mm. Battery type: 9V alkaline.