MACHINE-FRIENDLY BOBBINS - WonderFil pre-wound bobbins are wound with our 80wt DecoBob thread in a reusable plastic bobbin, which means there is no glue or wax holding it together making it machine-friendly. FINE WEIGHT THREAD - These bobbins minimizes the bulk in whatever you are doing. It also has the strength, versatility, and reliability you can count on. GREAT CHOICE - Uniformly wounded, these bobbins will get more consistency in all your stitches making it a great choice for your threading needs. HIGHER DENSITY - These bobbins come wound with a higher density of thread than when you wind your own bobbins on a domestic machine. VARIETY OF SIZES - The DecoBob Pre-wound Bobbins are available in Class 15, L and M. Plenty of sizes to choose from!