The modular system once developed by Robert "Bob" Moog went through a long production period between 1964 and 1981, including its development process. At that time, the new, electronic instrument was an avant-garde pioneering work that still had to be explained to the public, but ultimately found more and more interested parties.
The 995 attenuator from Behringer is a passive attenuator with three independent attenuators. An attenuator is always required when a module has no or too few attenuators (e.g. the 904A and 904B filters).
Behringer 995 Attenuators