Research COIL 9" (23 CM) concentric high-frequency (18.75 kHz). This high frequency plate has Characteristics similar to the 7.5 kHz, but it is more sensitive to small conductive targets. Waterproof and water proof, can be immersed in water up to 1 meter deep
This Research coil 9" (23 cm) concentrically is also available in three frequencies: 3 kHz (low frequency) - 7.5 kHz (medium frequency) - 18.75 kHz (high frequency) Compatible Metal Detectors: X-Terra 705 Gold, X-Terra 705, X-Terra 505, X-Terra 70 and X-Terra 50.