Simplex 4903-9236 Category : Simplex This unit has an electronic horn, as opposed to the electromechanical horn or speaker found in other rectangular Simplex notification appliances. Brand SimplexModel 4903-9236Manufacturer SimplexType Alarm (Horn/Strobe, 4-wire)
System Sensor MA-12/24L Category : System SensorIf I remember correctly, this sounder can be used for purposes other than fire protection.