The SMHAEN bobbin is a super functional, micro adjustable-tension fly tying tool featuring a unique design and highest quality workmanship. Its tension system allows you to adjust tension with only one finger, while still working on your fly. Thanks to the perfectly designed ergonomic frame shape, you don't even feel the internal tension system in your hand. A funnel at lower end of tube allows easy threading. The ceramic tube and the well balanced bobbin holder give you perfect thread control. Fits a range of spool sizes.