Class 15 bobbins
Imagine my surprise when there were a bunch of Class 15 bobbins included with the (old) Bernina 930 that I purchased!
These bobbins also fit my Singer 237 (a plain Jane machine from the early 1960's)
I just thought it was interesting.
I have not tried the Bernina bobbins from that machine on the Singer 237, though. Love that 237 - wish I could find a couple more of them!