Been reading a lot on how different fly fisherman rig a loop on the end of their fly lines to have a loop to attach a leader to and most are using a short piece of mono which they nail-knot to the end of their fly line and a Surgeons loop in the end of the mono for attaching a leader by loop-to-loop. I am trying to understand why most are using mono in the 25-30 pound test for this short connection. If you are saltwater fishing I can understand, but, for trout fishing, this pound test seems like over kill. Is there a reason for using this strong of mono or can a person use 12 to 15 pound test?

Just interested in the reason because I am not the "sharpest tool in the tool shed", so, educate me please!