I remember reading or hearing somewhere that Faraday took care of the labeling of Simplex’s devices. As we know, Faraday switched to that horn mechanism around 1994 when the ADA strobe mandates went into effect. At this point, Simplex had just released their 4900 Series plastic-body signals and nomenclature. Maybe Faraday still had -9838 labeled grilles to use up before the body migrated to the 4900 nomenclature, but ran out of the 6020/6120 mechanisms? Just a thought.