The 13316 Fil-Tec Clear Glide Black "A" Embroidery Bobbins are perfect for home sewing and embroidery machines. Made with high-tenacity polyester filament to avoid breakage, and wound onto plastic sided bobbin shells, they provide more stitches or yards per bobbin than most competitive or machine wound bobbins. Their compatibility with thread sensors make them ideal for all kinds of sewing and quilting projects. Not for multi-needle machines.