I was in the process of putting braided loops on all of my flylines as they needed new butt sections in the early eighties when I was fishing one of them on the little south branch of the Pere Marquette river early one spring. I was working my way downstream with a weighted wet fly when I felt a strong tug and then the line went slack like one of my knots had failed. The entire leader was gone. I got home and tested the leader connection on another line and it too pulled off as the heat shrink wrap failed. I took them off of my other rods and haven't used one since