Material:the thread spool savers are made of good quality silicone, having good flexibility and suitable for different sizes of home sewing or embroidery spools, but not suitable for commercial, industrial or large spools. The size of the silicone bobbin ring: 84*20mm; Package contents:12 silicone bobbin loops. Special design: compact and lightweight, the fixed spool will not be completely covered, you can also see the color of the line. Convenient to use: Simply stretch and attach them to the thread spools fast. Fits on standard thread racks ,a perfect accessory for sewing thread organizers or embroidery thread organizers. Applicable scope:thread spools savers can organize bobbins easily and keep the bobbin with relevant spool together better, a nice and useful accessory for a tailor to have, more convenience and save your time.