The Rolls MO2020 Test Tone Oscillator provides a sine and square wave output on 2 - 1/4" jacks. The frequency range is variable from 20Hz to 24kHz. The oscillator accepts a 1.2- to 5-volt DC input on a 1/4" jack for external frequency control, and a 10dB Output Pad is included to provide a -10dB reference signal.