Breathe life into all of your sewing projects with Quilters Select Prewound Bobbin Sets. This package of 40 class 15, prewound bobbins comes in a convenient plastic bobbin ring! The Quilters Select Prewound Bobbin Sets contain Para Polycotton Thread; a versatile, 80wt thread perfect for sewing, quilting, and crafting. Quilters Select Para-Cotton Thread is a poly-cotton blend that has been thermally treated; removing stretch, shrinkage, and weakness. This strong thread has a high sheen that gives every project a professional finish. Para-Cotton 440 yard spools are available to match each bobbin thread. Each Class 15 bobbin contains 135 yards of thread.