Threads won't tangle or unwind.
Shaped like half of a bagel and hollowed out, it is made of flexible rubbery plastic that expands to receive the bobbin and promptly snugs up around it. Size: 3/4" tall x 5 1/8" diameter *Bobbins not included.BobbinSaver(tm) Bobbin Holder holds metal or plastic bobbins of all different sizes! BobbinSaver(tm) holds over 20 bobbins securely.