I am a retired Home Economics teacher and for a few years before I retired my classroom had Bernina sewing machines. Kids kept losing the original bobbins, so I replaced them with another brand of bobbins that were the same size. The cheap bobbins worked fine. However, when we had the machines serviced, the Bernina dealer noticed the difference in bobbins and found damage to the machines. The repairs were expensive!! My recommendation from experience is use only Bernina bobbins.