1Designed by using principle that the density change of the substance below the surface of the detected object causes the detector frequency to change. 2Wall metal finder, selected high-quality plastic materials, durable in use and wear-resistant. 3Suitable for use in interior decoration structures, it can detect the position of metal and wood in the wall. 4When detecting the location of metal or wood, the detector has an audible and flashing alarm. 5Hand-held metal detector, small and light, simple and convenient operation, long service life. 6Just put the detector on tested surface, light up red LED and green LED, and hear "beep" sound. When red LED goes out, the sampling is normal. If the first red LED and the "beep" sound continue to light, the sampling failed.