Abstract: A fly line to leader connector comprising a leader with a modified, enlarged butt end, a securing collar, and a length of heat-shrinkable tubing, which contracts upon the application of heat. The result is a smooth, knotless connection between lines of dissimilar sizes and/or materials. Optionally, adhesive can be applied to the bore of the tubing. Additionally, shallow grooves can be inscribed on the surface of the end of the fly line.