Midi Sonde 8/33, 38mm (1.5"") diameter dual frequency 8kHz or 33kHz sonde used to trace drains, sewers and other non conductive utilities. Midi sonde has a M10 male thread with an additional female adapter and can be attached to a range of equipment including drain rods, boring tools and inspection cameras. Powered by 1 x AA alkaline battery, with a working depth range of 5 meters (16.5ft).