BALRAMA Super Scanner Hand Held Metal Detector with Beep Advanced...

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UltrasonicUltrasonic devices operate through emitting short wavelength, high frequency sound waves that are too high in pitch to be heard by the human ear (generally accepted to be frequencies greater than 20,000 Hz).Humans are usually unable to hear sounds higher than 20 kHz due to physiological limitations of the cochlea, though there is considerable variation between individuals, especially at such high frequencies. Some animals, such as bats, dogs, and rodents, can hear well into the ultrasonic range &Insects detect sound by special hairs or sensilla. Widely Use in home, warehouse, hotel, hospital or wherever you need it! It features a LED indicator light to let you know waves are working. A product for home use that works 24 hours a day,