Dr. Slick 4in Ceramic Bobbin Fly Tying Tool - Bobbins are a critical tool in tying since they must keep smooth tension on the thread spool and have super smooth inserts to apply the thread to your fly. These Bobbins have Delrin feet for smooth tension on the thread spool and have ceramic inserts for smooth application of thread to fly. These funnel-shaped inserts allow for a smoother application of thread or other materials as the bobbin is rotated, and they cause less breakage than traditional pipe or straight-edged inserts. Stainless Steel & Brass Finish Ceramic Inserts Delrin Feet