Doepfer's Module A-180-4 is a fourfold CV buffer. Buffers are required if the control voltage coming from a CV source shows a voltage drop in case of changing loads or due to other reasons a buffering is required. For the lower three units the input is normalled to the output of the above unit. That way the module can work as 1-in-4 buffered multiple provided that no signals are applied to the inputs of the three lower units.