Threaders Silicone Bobbin Clamps Keep your bobbin thread tails under control with the Threaders Silicone Bobbin Clamps! These clamps have been designed with the highest quality silicone that will hold bobbins tightly to prevent any unwinding. They\'re also coloured in the classic Crafter\'s purple shades, so they\'ll match up to the rest of your collection. Easy to use and ergonomically designed, these 20 bobbin clamps work with most preferred bobbin sizes, so they\'re perfect for the avid sewist or quilter!