Simplex 4903-9101 Category : Simplex I believe that this strobe plate was designed for use with a 2901-9838, but it could be used with a variety of different horns. Brand SimplexModel 4903-9101Manufacturer UnknownType Alarm (Strobe Plate)
Simplex 4901-9822 Category : SimplexThis is an electronic horn, not an electromechanical horn or a speaker.
Wheelock HNR Category : WheelockThis is from the Exceeder series. It is a horn-only version of the Wheelock HSR.
