Fisher Gemini-3 Metal Detector BATTERY TEST: Push button switch for battery strength indication on meter. SENSITIVITY: Large knob potentiometer. Controls sensitivity to targets and ground minerals. RANGE: Toggle switch for normal and high sensitivity levels. Four mode operation: Inductive Trace, Conductive Trace, Wide Scan Inductive Trace and Narrow Scan Inductive Trace. VCO audio target response for precision pinpointing