Countryman User Pricelist Frequency Response: Omnidirectional: 20 Hz to 20 kHz Directional: 30 Hz to 15 kHz Operating Current: 500 uA Operating Voltage: 1 to 2 Volts Power Supply Voltage: +3V with 2.7 kOhm load +5V with 6.8 kOhm load +9V with 15 kOhm load ... More @Wikipedia
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