These looked like they would be exactly what I needed. However, the hole in the Simthread Embroidery spool was too large the the bobbin holder would not stay put.I like that fact my bobbin are read to use with matching thread.These work fairly well depending on the size of the hole in the spool. Some spools are too narrow so I just stacked the bobbins on another thread pole. Would be nice to have two sizes.I sew alot!!! Solved my problen of tangling threads and trying to find matching bobbin thread to spools.The idea is great but I did not realize the thread spools have different sized holes. They do work well on most of my spools of thread.I really like these bobbin holders. They fit right on the top of your thread so that the bobbin and the thread are together. You can see this in one of the photos provided. I have found that some big the thread holes are too big for them so I just put a little paper in the hole and that fixes the problem. I like this type because I can use my thread rack with them. They seem to be the only ones I found that you can use in the rack. All if the others go into the thread and prevent you from using the rack. So, I am pleased with their shape, how easy they are to use and the fact the thread does not hang when in use.I love these bobbin holders. I was concerned at first because of some negative reviews that stated they didn’t fit their thread spools, but decided to take my chances and order them anyway. I’m so glad I did. I’m all about organization and I hated having to hunt for the right color bobbin every time I changed thread. Now my thread and bobbins are all together sitting neatly in my spool rack. I’m so happy. I will buy again.Great for keeping spools of thread with the bobbins. Easy to use and a good value.