Superior Threads L-Style Pre Wound Bobbin Assortment Prewound Bobbins Bottom Line Thread 35ct in Red Bobbin Saver Cardboard-sided prewound bobbins may be used with the cardboard sides on or with the sides removed. 35 colors from Superior Threads Frostings Line. L style prewound bobbins with Superior Threads MasterPiece Thread. MasterPiece is #60 100% Polyester, 118 yds per bobbin.. Tucked into a BobbinSaver for safe keeping and instant access to all colors!