In stud mode, there are 3 scan modes to choose from to get the right thickness. 1/2inch stud scan mode detects wood or metal studs up to 1/2inch (13mm) deep. 1inch stud scan mode detects wood or metal studs up to 1inch (25mm) deep. 1 1/2inch stud scan mode detects wood or metal studs up to 1 1/2inch (38mm) deep. If you do not know the depth of detection, it is recommended to use 1/2inch scan mode first. When 1/2inch scan mode is not detected, use 1inch or 1 1/2inch scan mode. Detection depth of magnetic metals up to 3.2 inches (80mm) (15mm diameter galvanized steel pipe). It can detect non-magnetic metallic copper pipe up to 2.4 inches (60 mm) (13 mm diameter). AC modes detects unshielded AC wire up to 2 inches (51mm) deep. This metal depth indicator has green backlight and low voltage indicator light. It is equipped with battery. This electronic stud sensor beam finder is quick to locate wood, metal and AC wires hidden in the walls, floors and ceilings of your home. It works on lath, wallpaper, wooden floors, acoustic ceilings, painted walls and more. Avoid dangers when you install , cabinets, garage racks, and more. Specification: Product Name: Stud Finder Wall Scanner Material: ABS+metal Size: 165x74x40MM /6.4x2.9x1.5 inches Battery type: 9V battery Working current: Less than 50ma Off current: Less than 10UA Automatic shutdown time: 3 minutes Color: as shown Package Contents: 1 x Stud Finder Wall Scanner Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.