Clear Spun Polyester #90 Bobbin, 12 Pack, 15/A Class White Fil-Tec Clear-Spun Plastic-Sided Ready Wound Bobbins. 12 Bobbins in pack. Class-15/A White. 95 yards per bobbin. High-Tenacity Spun Polyester Yarn. 100 DTEX/2. Clear-Spun's clear plastic-sides work ideally with thread sensors and allows the operator to easily see how much bobbin thread remains. Clear-Spun offer considerably more stitches per bobbin than machine-wound bobbins, and sews completely out with little or no tension variation. Optimized for domestic sewing machines that utilize a drop-in style bobbin.