Stud detection helps easily locate and detect wood and metal studs, beams, and joists up to ¾" deep. Measures moisture levels from 8% to 22% present in wood, drywall, carpets, and more to find if potentially damaging excess moisture is present to prevent wet rot, mold, and mildew. Metal detection helps detect and locate hidden metals, steel, and copper pipes behind walls up to 2" deep. Voltage detection helps locate live AC wires behind walls, ceilings, and floors up to 2" deep. Requires one 9-volt battery (not included).