Space Age AV32+2DCD That is an electromechanical horn on the rear of the strobe plate. Brand Space Age Electronics
GE 521BXT Category : GEI think that this smoke detector might be intended for use in security systems.
Notifier F67ODT Category : NotifierF67ODT likely isn’t the model number of the unit as it was just a random number stamped on the wall...
Gaylord NC-1357A Category : GaylordThis is a rebranded EST/Edwards 270-SPO for use in some sort of ventilator system.