This sized pusher cap was used on some 60s/70s Breitling and Wakmann (and others) chronographs but I cannot tell you for sure which models. They were not always consistent with the pushers they used. It is a way more complicated issue than most people realize because they used pushers from several suppliers and they were not standardized.

: Thanks Craig, really appreciate the information (even if it
: probably doesn't fall under the heading of 'good news'!). Don't
: suppose they were shared with any other vintage models?

: Cheers

: Mark