Interphone Microphone Fit with:TM-231/241 1.Clear sound performance 2.Comfortable holding. Interphone MicrophoneMicrophoneImpedance: ... :-36dB+/--2dB,Frequency response:20Hz-1.6KHzFit withTM Series: TM-231, TM-241, TM-731A, TM-631A, TM-201A, TM-401A ... TC3000 TC3600 etc...SM10R2 Fit HYT TM600,TM610 etc...NSP-100,NSP-150V NA-750 NA-650 EXTERNAL SPEAKER Interphone Microphone ...