My Singer is also very particular about bobbins. It's not just how big around they are, either. They are slightly curved--like a yo-you not flat like most bobbins & they are tinted a slight purple color. They will work in my Elna but my Elna bobbins nor plastic prewounds will work in the Singer. A dealer told me they prefer the cardboard prewounds and tear off the top side. I use my Elna for quilting most of the time so I never got around to testing the cardboard prewounds. I do know that the Singer dealers carried the correct size bobbins for my machine--Quantum Futura CE-200. I don't know if the new models use the same bobbins as mine however. The machine looks similar but I didn't take out the bobbin to compare.