System Sensor 2151 This smoke detector is fairly rare. Brand System SensorModel 2151Manufacturer System SensorType Smoke Detector (Photoelectric, 4-wire)
Ademco 532 Category : AdemcoThe only place I’ve ever seen an Ademco re-branded BG-10 has been on this particular unit.
Cerberus Pyrotronics MS-151 Category : Cerberus PyrotronicsThis Cerberus Pyrotornics MS-151 is in a bit better shape than my other one.