Wheelock MT4-24-LSM Category : Wheelock This is an earlier version of the MT. I do have two of these. Brand WheelockModel MT4-24-LSMManufacturer WheelockType Alarm (Horn/Strobe)
GE 521BXT Category : GEI think that this smoke detector might be intended for use in security systems.
Wheelock ET-1080-WS-24 Category : WheelockYou can’t really tell from the pictures, but the strobe is practically falling out of this particular unit.