Waveforms generator to test a Hi Fi system. You connect the headphone wire to the AUX input of the Hi Fi. Available waveforms: Sine, Triangle, Ramp-Up, Ramp-Down, Square Wave white and pink noise. Frequencies range from 16Hz to the maximum possible for the device, selectable in steps of 1, 10, 100, 1000, 10000 Hz by pick number.