What you get: 75 Size M black prewound bobbins, 40S/2 low-stretch spun polyester (#60 / 40WT) on a plastic-sided shell, about 105 yards each - roughly 1.5x the yardage of a Size A bobbin in the same thread weight. Made by Doublelin, an embroidery machine manufacturer since 1989.
Size M is not the same as Size A or Size L. Size M (also Class M, Style M, or M-Class) measures 1-1/64 in (2.60 cm) diameter x 7/16 in (1.10 cm) height. Size A and Size L have different dimensions and are not interchangeable.
For longarm quilting on dark quilts and heavier-thread sewing. 40S/2 (#60 / 40WT) is a standard sewing weight. It suits free-motion edge-to-edge quilting on dark fabric, custom quilting on midnight backings, dark quilt piecing, and garment sewing on dark wovens including denim, on Handi Quilter, Innova, Gammill, APQS, Tin Lizzie, and Bernina machines. Black is dyed for use with dark quilt tops where bobbin show-through can be a concern; pair with dark top thread for tonally matched backs.
Match the thread weight. Pair the 40S/2 bobbin with 40WT or heavier top thread so the lock stitch sits centered in the fabric for flat, even stitches. This is not the right weight for sealed-bobbin-case embroidery machines that call for a finer #90 (50WT) bobbin, or for Tajima / Barudan large-bobbin industrial embroidery - for those, choose a Doublelin 60S/2 (MPB-60S2 black).
How to confirm fit: check your machine manual for Size M / Class M and a #60 or 40WT bobbin, view our compatibility photos, or measure a bobbin to 1-1/64 in diameter x 7/16 in height. Not for home sewing machines that take Size A (Class 15) or Size L bobbins.
FAQ
Q: Will these fit my Handi Quilter Avante or Amara? Yes - all Handi Quilter machines use Size M / Class M bobbins.
Q: For a midnight or dark quilt back, will black work? Yes - black is dyed for dark fabric where show-through is a concern; pair with dark top thread for matched results.
Q: My manual says #60 - is this right? Yes. #60 is the Japanese Gunze count, equal to 40S/2, about 40WT in the US system.
Q: Are #60 and 60WT the same? No - #60 is about 40WT; 60WT is a different, finer thread.
Q: Can I use these for industrial embroidery? For Tajima / Barudan embroidery use 60S/2 (#90 / 50WT) instead - see our MPB-60S2.
Q: Is the black colorfast? The black uses a reactive dye process commonly used for industrial textile applications. We recommend testing on your fabric before production runs.
All brand names referenced are for compatibility purposes only. No affiliation or endorsement is implied.