No. 50 Egyptian Long-staple Cotton. The perfect cotton pre-wound for domestic machines, Clear-Quilt bobbins are wound on a plastic-sided bobbin shell. Their Egyptian long-staple fibers ensure strength and wash-ability. They are responsive to machine thread sensors so you don't have to worry about your yardage. Clear-Quilt offers more stitches per bobbin than competitive and machine-wound bobbins.