Simplex 4904-9137 This is, in fact, a Simplex 4904-9137. It’s just missing its housing. Brand SimplexModel 4904-9137Manufacturer SimplexType Alarm (Strobe)
System Sensor SP1W2475ADA Category : System SensorThe strobe portion can detach from the speaker body.
Wheelock 7002T-24 Category : WheelockEach 7002T-24 has a somewhat different pitch, so I’ve kept several that sound different from each other.