Module A-118 is (as you might have guessed) a noise and random voltage generator. It produces three types of signal: white noise, colored noise, and random voltage.
White and colored noise can be used as audio sources, and also, in conjunction with a sample & hold module, as control voltages, and the random voltage is a useful source of voltage control, especially for its low frequency content.
The A-118 gives you the ability to mix the relative amounts of Red (low frequency component) and Blue noise (high frequency component) in the colored noise output.
There are knobs to control the rate of change and amplitude of the random voltage, and two LEDs indicate the state of the voltage at any one time.