All Metal: a non-discriminate control setting that accepts detection of all metal objects, including ferrous (i.e. iron-containing) ground minerals.
Audio ID: also known as tone ID, this detector feature identifies targets via a tone that corresponds to their conductivity.
Beat-frequency Oscillation (BFO): a beat-frequency oscillator is the most basic type of metal detector. A BFO detector works by measuring the difference in frequency between its search coil and a small reference coil in its control box. This difference creates an audible signal or "beat," which varies in tone and duration when metals or minerals affect the frequency of the search coil. BFO metal detectors are less expensive than PI or VLF detectors, but also less accurate.
Cache: a cache is a group of objects that has been intentionally hidden or buried.
Clad: coin detectors often discover clad, which is a term for coins that are still in circulation. With clad coins, a surface metal covers or clads a base metal. Pennies, for example, used to be made from copper, but are now copper-clad zinc.