The SUB-SCANNER™ M12™ Lithium-Ion Detection Tool is a heavy duty pistol grip detection tool for professional commercial and industrial applications. Powered by the Milwaukee M12™ REDLITHIUM ™ battery, the 2291-21 can detect rebar up to 6" deep in concrete, as well as the location of wood and metal studs beneath drywall. In addition, the SUB-SCANNER™ M12™ Lithium-Ion Detection Tool has a four wheel design for durability and smooth, accurate measurement.