Hmmm... The taller bobbins are usually for oscillating hook machines. And they usually have 10 holes for Singer and other brand machines, or 7 holes for Berninas. ...although there are some drop-in Singer machines that take the 10-hole bobbin. And the bobbins for oscillating hooks sometimes don't have any holes. If they're rounded on both ends, they are for the older Singers -- although some older Singers do take the 10-hole bobbins. Plastic bobbins are usually for Viking, Husqvarna, Pfaff, Janome and BabyLock. ...and all of the new, cheap Singer and Brother machines. Viking/Husqvarna bobbins are very specific, and have the logo on the plastic. So if it's metal, it's from something older or a Bernina. Singer Featherweights have a short bobbin with lots of holes. Older Vikings have a specific metal bobbin, that's usually flat on both sides, with a little slot.
It's so confusing!
When you put the bobbin in the bobbin case, it should spin freely, and have a very small space above the bobbin, and not have a lot of extra space on the sides.