Jumbo Pre-Wound Bobbins by Fil Tec

We use this jumbo (size M) pre-wound bobbin in our Gammill Long-arm Sewing Machines.  We generally use white 99% of the time. No. 60 Filament Polyester thread - 100 count.  Fil-Tec by Bobbin Central's patented magnetic core creates consistent delivery through the entire bobbin. No more interruptions for tension adjustments as your bobbin gets smaller. Magnetic core prevents backlash or over-spin and eliminates the need for backlash springs. Magna-Glide is the original high-yield magnetic-core bobbins.