Simplex 4903-9101 Clearly, this alarm is not in its prime. Brand SimplexModel 4903-9101Manufacturer UnknownType Alarm (Strobe Plate)
Simplex 4259-25 Category : SimplexThis is a photoelectric smoke detector from the mid to late 1970’s.
Amseco BZ-51-PC2 Category : AmsecoI like the grille, or in other words, have nothing special to say about this particular unit.