3 in 1 Detector Metal Wood Studs AC Voltage Scanner Detection Depth Stud Mode : Wood stud of 30 x 30mm : 18mm Metal Mode : Iron pipe of 25 : 30mm Fuse Protection for"20A"Terminal Inputs: 20A, 1000V,FAST, Min.Interrupt Rating 20000A Operation Condition : -7~40C below 75% RH Overrange Indication : "OL" shown on the screen Battery : 1 x 9V Battery