I use the round rings too. Different color ring for each machine. I can see the color thread on the bobbins in a glance to match the spool thread. The bobbins will not fall out of the rings. I put the bobbins with the thread end down into the ring so no loose threads hanging out. I've been using up my filled bobbins and now buy Superior pre filled bobbins and Glide magna bobbins. I wished I had started using the prefills long ago!