Coinmaster Classic II is an old but popular make of metal detectors from White Electronics, the American metal detector manufacturer. The Classic II detector is available in a number of variations (Classic I, Classic III). It can be used to detect coins and small jewelry pieces. The Coinmaster Classic II metal detector features an On/OFF sensitivity control knob, a Discrimination level control knob, a toggle selection switch for Discrimination or All-Metal modes, a search coil, and a headphone jack. The portable handheld unit extends out to 50 inches or collapses down to 43 inches. Other metal detectors from White Electronics include the PRIZM series, the Matrix series, and so on. Besides White Electronics, other metal detector manufacturers include Garrett, Fieldmaster, and others. Metal detectors are machines that use electromagnetic induction to detect metals. These machines are used in detecting land mines and weapons, at airports, in archeology, in 'treasure hunting', and so on. A typical metal detector consists of the following parts: a Stabilizer that keeps the unit stable; the Control Box that contains the circuitry, controls, speaker, batteries, and the microprocessor; the Search Coil that actually identifies the metal; and the Shaft that connects the control box and the coil. There may also be a Jack for connecting headphones.