Magna-Glide Delights are the original high-yield magnetic-core prewound bobbins from Fil-Tec. The patented magnetic core delivers consistent thread tension from a full bobbin down to the last yard — no mid-project tension adjustments, no backlash, no over-spin, and no need for backlash springs. Each jar contains 10 Class L bobbins wound with smooth 40wt filament polyester, sized to fit most domestic sewing and embroidery machines as well as many longarm quilting machines. Fiber: Filament polyester Thread weight: 40wt, 2 ply Bobbin style: Class L, magnetic core Length per bobbin: 72 yards Recommended needle: 65/9 (domestic), 4.0 (longarm) Use: Bobbin thread for quilting, embroidery, and general sewing Magnetic-core bobbins keep delivery even as the bobbin empties, which is why longarm quilters and embroiderers rely on Magna-Glide for stitch consistency across large projects.