Know The Apparatus: This unit is 3 in 1Metal/Voltage/Stud Detetor. It uses electronic signals to locate the exact position of studs. ceilling joist AC wires and metal through.Drywall, concrete and other common wall materials . Once the edge of a stud has been detected , it emits audio and visual(LCD Display) that allow you to pinpoint its center position . This unit is an perfect tool for DUY fans , professional eletrician and user in decoration field. Function Description: 1. Detect STUD 2. Detect metal 3. Detect AC Live Wires 4. Using metal detect function to find hidden metal pipe, rivet or fixture in the wall 5. Auto power off (No operation ) Metal detection: maximum depth 30MM : maximum depth 30MM1/2inch Wood detection (3 distance detection): (13MM)1inch (25MM)3/2inch (38MM) Note: Ship without battery use 1x9V batteryI notincluded Material: plastic colour: yellow Package Contents: 1 x Metal Detector 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.