10-Inch Coil Model Fisher CZ-21 Underwater Metal Detector A professional dual-frequency metal detector built for beaches, freshwater, saltwater, land hunting and serious underwater detecting at depths of up to 250 feet. Dual 5 kHz and 15 kHz Submersible to 250 Feet 3-Tone Audio Target ID 10-Inch Searchcoil Please note: This listing is for the CZ-21 model with the larger 10-inch-class searchcoil. The searchcoil and waterproof headphones are permanently attached to maintain the detector’s underwater integrity. Serious Performance Above and Below the Water The Fisher CZ-21 is designed for treasure hunters who need reliable performance in demanding environments. Its waterproof control housing can be submerged to depths of up to 250 feet, making it suitable for scuba diving, shoreline hunting, surf detecting, freshwater recovery and searching wet saltwater beaches. Unlike a conventional single-frequency VLF detector, the CZ-21 simultaneously operates at 5 kHz and 15 kHz. The two frequencies provide additional target information and help the detector respond to a broad range of targets, from higher-conductive coins and silver to smaller and lower-conductive jewelry. This 10-inch coil version provides increased ground coverage and is an excellent choice for hunters searching larger beaches, open swimming areas and underwater locations where covering more ground efficiently is important. Key Features Designed for dependable target identification, deep searching and stable operation in difficult saltwater conditions. ≈ Dual-Frequency Operation Simultaneous 5 kHz and 15 kHz VLF frequencies provide additional target information for detecting coins, jewelry, relics and other valuables. 💧 Waterproof to 250 Feet The fully submersible construction is made for beach hunters, shallow-water searchers and divers working in both freshwater and saltwater. 🔊 3-Tone Target Identification Low, medium and high audio tones help classify iron, foil, pull tabs, coins and jewelry without requiring a visual display. ◎ 10-Inch Searchcoil The larger concentric searchcoil offers efficient coverage for beaches, swimming areas and underwater locations while retaining precise pinpointing capability. ⌖ V.C.O. Pinpoint Mode The no-motion pinpoint mode increases in pitch and volume as the center of the searchcoil approaches the target. ⚙ Manual Ground Balance Adjust the CZ-21 for changing ground conditions to reduce unwanted ground responses and maintain dependable performance. 🌊 Saltwater Compensation Fisher’s signal analysis helps cancel the conductive response of saltwater for more stable operation on wet sand, in the surf and below the surface. ↗ Faint-Target Audio Boost Volume settings above level 5 increase the response from faint and deeper targets while keeping strong target signals at a controlled volume. ! Large-Target Alert A distinctive bell tone alerts the user when a large, shallow target overloads the identification circuit. Three Operating Modes Target-ID Mode: Silent-search, slow-motion discrimination with three-tone audio identification. Auto-Tune Mode: Threshold-based all-metal mode designed for maximum sensitivity and a wider search pattern. Pinpoint Mode: No-motion all-metal pinpointing with a variable pitch and volume response. Built for Different Hunting Environments Saltwater beaches and wet sand Freshwater lakes and swimming areas Surf and shallow-water hunting Scuba diving and underwater recovery Coin and jewelry hunting on land Relic hunting in suitable ground conditions Designed for Underwater Treasure Recovery The CZ-21 can be shortened for diving, extended for land use or configured with the control housing mounted on a belt for reduced arm fatigue during land and shallow-water hunting. Permanently attached waterproof headphones provide direct audio feedback in noisy surf and underwater environments. Technical Specifications Technology Dual-Frequency VLF Operating Frequencies 5 kHz and 15 kHz Searchcoil 10-Inch-Class Concentric Coil Searchcoil Connection Permanently Attached Waterproof Rating Submersible to 250 Feet Operating Modes Target-ID, Auto-Tune and Pinpoint Target Identification 3-Tone Audio Plus Bell Tone Ground Balance Manual Discrimination 7 Preset Control Positions Sensitivity 10-Level Adjustment Volume 10-Level Adjustment Headphones Permanently Attached Waterproof Power 4 × 9V Batteries Alkaline Battery Life Approximately 35–55 Hours Extended Length Approximately 50 Inches Collapsed Length Approximately 30 Inches Complete Weight Approximately 6 lb. 1 oz. Control Housing Hip-Mountable on Land Country of Origin USA Manufacturer Warranty 2 Years Package Includes Fisher CZ-21 Control Housing 10-Inch-Class Waterproof Searchcoil Permanently Attached Waterproof Headphones Adjustable Detector Shaft and Armrest Hip-Mount Belt Clip Searchcoil Hardware Operating Instructions Manufacturer Warranty Four 9V batteries are required and are not included. Frequently Asked Questions Can the Fisher CZ-21 be used in saltwater? Yes. The CZ-21 is designed for freshwater and saltwater operation. Its dual-frequency system and saltwater compensation help reduce false responses caused by conductive wet sand and saltwater. How deep can the CZ-21 be submerged? The detector is rated for underwater use at depths of up to 250 feet when properly maintained and used according to the manufacturer’s instructions. What is the benefit of the 10-inch coil? The larger coil covers more ground with each sweep and is well suited for open beaches, swimming areas and underwater locations. It may also provide increased detection depth on suitable targets under favorable conditions. Does the CZ-21 have a visual Target ID screen? No. The CZ-21 uses audio target identification. Low, medium and high tones identify different conductivity ranges, while a bell tone warns of a large, shallow target. Can the searchcoil or headphones be removed? No. The waterproof searchcoil cable and headphones are permanently attached and are not designed to be changed by the user. Can the control housing be hip-mounted? Yes. The housing can be hip-mounted for land and shallow-water searching to reduce weight on the detector shaft. Fisher does not recommend hip-mounting the control housing while scuba diving. What batteries does the CZ-21 use? The CZ-21 operates on four 9V batteries. Alkaline batteries are recommended and provide approximately 35 to 55 hours of operation, depending on conditions and settings. Built for Serious Beach and Underwater Detecting The Fisher CZ-21 combines proven dual-frequency performance, audio target identification and professional underwater construction in a detector designed for demanding saltwater, freshwater and land hunting. This model includes the larger 10-inch-class searchcoil for increased coverage in open hunting areas.