I think you're referring to this one?
http://www.superiorthreads.com/media...ility-list.pdf

Somewhere, I'm not sure where, I would think it's FilTec or Superior, I read that something like 80% of machines take an "L" bobbin, so if I'm ever in doubt, I try one of those first. It's the same diameter as a 15, but it's shorter. My Janome that takes Class 15 bobbins (they have their own special number so they can try to get you to buy their bobbins instead of a regular class 15, just like Pfaff's 9033 is an L bobbin, etc) has no trouble at all with the L prewounds I threw in it.

I love that one Tammi. I made a folder and included some photos and info. It's nice to be able to SEE pics and try to match up a bobbin but also to have a chart of what machine takes what bobbins. I see, L's M's and Class 15's, but what is a "class 15 CB bobbin" under the Berninas?

Looks like a metal bobbin.
http://www.superiorthreads.com/educa...rnina-bobbins/

I think a while ago we determined that CB stood for "Central Bobbin", at least for the Singers.
http://www.quiltingboard.com/vintage...e-t216990.html

I honestly don't know why Bernina made that distinction. I can't see a difference between those 15 CB bobbins and a regular 15 bobbin. I've ordered the actual ones for a customer at one point and there was no discernible difference that I could come up with (I didn't pull out calipers) besides maybe the number of holes on each side of the bobbin which should make little to no difference. I think it's mostly a "if we make it sound different, they'll buy our bobbins instead of the regular class 15 bobbins" just like Pfaff, Kenmore, Janome, etc.