the cal. 12 is a prototype, among the watches mass produced & delivered:

100-200 pieces 1551 SGSZ "Heuer Sternzeit"
255 pieces 1150 SG "Leonidas" R222 (out of about 11k under this model ref.)
550 pieces (apparently only about 350 delivered) Tengler Sternzeit

: Let's make this short and sweet - I want to add a Bund to my
: collection, I know they're easy'ish to find as are their spare
: parts and they're always looking disturbingly 'fresh'
: ...... but for some reason I still want one - so which is the rarer
: version to buy; do you know?
: Seems to me we all know the different dial marking variants, but
: which are the rarer? Or are they all much of a muchness and its
: down to personal preference?

: Thanks for succinct answers, I'm not looking for a massive
: discussion, seems to me there are far more interesting Heuer
: things to chat about!
: Ben