Hearing Sound Amplifier, For Watching TV and Listening to Music, 20 Hours of Use

High Frequency Compensation = Beep Twice. Press "-" Button, Reverse Cycle, (Mode 3→2→1). Sound Device. 3 Modes - Press Button 3 Seconds to Change Mode. 1-Normal; 2-High Frequency Compensation; 3-Low Frequency Compensation.

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