This wall metal detector is crafted from quality material, shock-resistant, and wear-resistant, can provide long service time. Uses an electronic signal to locate the edges of a stud or joist, and its signal can pass through drywall and plywood, and the designed depth is up to 3/4inches. Easy to use, when it detects the edges of the stud, the 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. Note: While calibrating, the 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