Keep from the object to be measured, turn on the knob switch and adjust it slowly, so it is just in the state of no sound and no light, and detect metal When the detector's metal detection head (METAL) is moved parallel to the surface of the object to be measured, if the voltage loop is detected, the detector voltage The detection part (VOLTAGE) moves parallel to the surface of the object to be measured. When the detector is to a metal object or a voltage circuit, it will flash Light and sound. When there is no metal object or voltage circuit nearby, it will not flash and sound. When the test is over, please cut off the . The detector cannot test the AC voltage in metal pipes, metal walls or deep parts. supply: 6F22 type 9V battery (battery not included) Product size: 150x78x24mm Standard configuration: bare watch (no battery inside), English manual Product advantages: suitable for in interior decoration structures, it can detect the position of metal and wires in the wall, when metal and voltage are sensed, the instrument will flash and sound Product technical features: Voltage test: wire above AC 100V, depth 30mm Colour:black Material:plastic Package Contents: 1 * metal detector(Without battery) 1 * English manual Only the above package content, other products are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.