Calibration switch for reference to help interpretation of waveforms
Battery-powered audio unit, which can be hand-held, hung round the
neck or clipped to a belt or pocket
Auto power shut-off facility for maximum battery life
Battery low indicator
Can be connected to mains through A.C.Adaptor
Built-in speaker
Headset/Headphones attachment
Any chart recorder (eg. ECG recorder) for waveform analysis