Leader Loops Tips
Most fly anglers use a braided leader loop between the fly line and the leader.
The leader loop helps to transfer the energy from the fly line to the leader, giving longer casts and better leader turnover.
The loop on the end of the braid makes it very simple to join leaders to the fly without tying large bulky knots in the fly line that can snag on the rod rings. Not what you want to happen when you're bringing a large fish to the net.
For extra security, add a small drop of super glue on the end of the braid just before covering with the rubber sleeve. A wipe of the fly line end with a damp cloth before starting will prevent the line lubricants from interfering with the glue join.