Technical Bosch Spark Plug

Brought home our 30 Coupe a couple weeks ago that came with a bunch of extra parts and pieces in boxes. My boy and I sat down this afternoon to sort through all we had and came across 4 of these Bosch plugs that I can’t find any info on. The stamping says:

BOSCH Z 120/1

ROBERT BOSCH
A-G

GERMANY
IMPORTED ALLEMAGNE

 

With a bit of searching you might find some info on this site.
https://www.gsparkplug.com/

 

Nice car. Your plug looks a lot like this sign from Walmart. Might get you started,anyway.
https://www.walmart.com/ip/1914-Bosch-Spark-Plugs-Metal-Sign-10x14-inch-Vintage-Look/720661316

 

Good article https://www.gasenginemagazine.com/equipment/collecting-antique-spark-plugs/

Spark Plug Collectors of America http://www.spcoa.net/