Dr. Slick Titanium Bobbins- Bobbins are one of the most critical tools in fly tying since they must keep smooth tension on the thread spool and have super smooth inserts to apply the thread to your fly properly. Dr. Slick Titanium Bobbins are the choice of many tyers. Superb quality and a storied tradition. Dual titanium inserts and Delrin Feet. The insert has a raised, micro pebbled or egg carton pattern which cuts down on surface tension. Ridiculously slick!. They come in 3" and 4". lengths.