Bobbins are the 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. To this end, we have created three series of bobbins that handle these tasks with ease. All have delrin feet for smooth tension on the thread spool. 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 Dual Glass Inserts Delrin Feet