This wall metal detector is crafted from quality material, -resistant, and wear-resistant, can provide long service time. Uses an electronic signal to locate edges of a stud or joist, and its signal can pass through drywall and plywood, and designed depth is up to 3/4inches. Easy to use, when it detects edges of stud, red LED will light up and make a sound. Wide applications, suitable for different wall appearances such as wall siding, wallpapered wood floors, sound-absorbing ceilings, painted walls, etc. Features: Crafted from quality material, -resistant, and wear-resistant, can provide long service time. Uses an electronic signal to locate edges of a stud or joist, and its signal can pass through drywall and plywood, and designed depth is up to 3/4inches. Easy to use, when it detects edges of stud, red LED will light up and make a sound. Use handy pencil notch located at upper of unit to mark stud edges. Repeat from other side of stud. Coming from opposite direction, mark other edges of stud. midpoint of two marks indicates stud center. Wide applications, suitable for different wall appearances such as wall siding, wallpapered wood floors, sound-absorbing ceilings, painted walls, etc. Note: While calibrating, stud sensor can not be placed directly over a stud, dense material such as metal, or over a wet or newly painted area, or it will not properly calibrate. Specifications: Name: Wall Metal Detector Material: plastics Battery: 1 * 9V battery (not included) Color: red, orange, yellow, blue (optional) Item size: 136 * 23 * 50mm / 5.35 * 0.91 * 1.97in Item weight: 80g / ounce Package size: 144 * 26 * 55mm / 5.67 * 1.02 * 2.17in Package weight: 90g / 2.82ounce Packing List: 1 * Wall Metal Detector