Most fly lines these days already come with welded loops at the ends for the easy attachment of backing and leaders. If you fish as much as I do though, eventually they get worn out and need to be replaced. Most anglers just use a standard albright knot or nail knot to fix this. It works perfectly fine, but I prefer instead to tie my own fly line loops with a fly tying bobbin and thread. Done correctly, it will provide a stronger connection to your leader than the manufacturers welded loops ...
