Coats Dual Duty L-Style Pre Wound Cotton Corespun Bobbin ~ Rustana Red ~ Prewound Bobbins 12ct Cardboard-sided prewound bobbins may be used with the cardboard sides on or with the sides removed. Rustana Red Spun Polyester Corespun Disc Bobbins. 94 yards per bobbin. Up to three times more than when you wind your own! Size / Weight #47 thread. (Tex 21) Don't mess around with filling bobbins. Save time buying pre-wound!