I believe any BG-12 that has “PDI” (which stands for “Pittway Distribution, Inc.”, a division of Pittway Corporation who owned Fire-Lite, Notifier, & Silent Knight at the time (all of whom have sold the BG-12 under their names) on its label was made before Honeywell’s 2000 acquisition of the Pittway Corporation: if it says just “Fire-Lite” or just “Notifier/Notifier Fire Systems” on the front that may also be a pre-Honeywell version as well, but I believe unless it specifically says “PDI” on the inside it’s not a pre-Honeywell version.