Two AA alkaline batteries

enough for a full week of prospecting trips without a recharge

and Garrett's Ground Balance Window settings let us spread the ground balance across mixed mineralization so the threshold stays smooth instead of breaking up

This combo ships with both a 6-inch and a 10-inch elliptical waterproof coil

Audio: VCO (Voltage Controlled Oscillator) + 2-Tone (Low and High)

Fisher CZ-21 Dual-Frequency Underwater Metal Detector with 10.5" Concentric Waterproof Coil bone-conductor-required Two AA alkaline batteriesThe Fisher CZ 21, known to divers as the CZ21 QuickSilver, is a dual frequency underwater metal detector submersible to 250 feet, built for scuba divers and surf hunters who work saltwater beaches, freshwater lakes, and deep dive sites. This version ships with the larger 10. 5 inch concentric waterproof coil, which covers more ground per sweep and reaches a little deeper on open sand than the 8 inch, making it the choice for wide beach and open bottom