This is a modification that you can add to your yarn bobbin clips to keep the yarn from sliding off the end of the clip. It fits into the clip of the essentials brand clips from the dollar store or on Amazon. You will need 2 per clip. There are 2 thing files: one with 12 items which is enough for one package of clips or 36 items which is enough for 3 packages of clips.

https://www.amazon.com/Essentials-Jumbo-Plastic-Clothespins-TOTAL-Blue/dp/B01N213SSC/ref=sr_1_9?keywords=essentials+laundry+clips&qid=1576861119&sr=8-9