WonderFil DecoBob Prewound Bobbins Size L Master Set. 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 which also makes for happy machines. DecoBob makes for an ideal bobbin thread as using a finer weight thread will also minimize the bulk in whatever you are doing, however DecoBob also has the strength, versatility, and reliability you can count on. Pre-wounds are a fantastic choice because they come wound uniformly meaning you will get more consistency in all your stitches, which is especially noticeable when doing embroidery. They also come wound with a higher density of thread than when you wind your own bobbins on a domestic machine. Made of: 2-ply Cottonized Polyester Thread. Assorted colors. Size: Size L. 40 Bobbins per pack. CHK-DBPL-MS