Enjoy the Quilters Select Class 15 Prewound Bobbins (10 pk) and stop wasting time winding bobbins to coordinate with your projects. The Quilters Select Prewound Bobbin Sets contain Para Polycotton Thread; a versatile, 80wt thread perfect for sewing, quilting, and crafting. This polycotton blend has been thermally treated, removing stretch, shrinkage, and weakness, and it has a high sheen that gives every project a professional finish. Para Polycotton Thread 440-yard spools are available to match each bobbin thread. Each Class 15 bobbin contains 135 yards of thread.