The Super Scanner metal detector discovers medium-size pistols from a distance of 9"; large pocket knives, up to 6"; razor blades, 3"; hatpins, 1". The Super Scanner features a reduction switch to help minimize rebar sensitivity interference while scanning at ankle level. This metal detector has a large scanning surface for quick, yet thorough scanning. Features: Automatic retuning (no adjustments ever needed). Sensitivity can be limited if ambient metal causes interference. Automatic battery check. No tools are required to change batteries. Is lightweight, yet very rugged. Housing constructed of polycarbonate-fiber reinforced material. Utilizes surface mount electronic component technology.