This article covers loops used for connecting fly lines to backing and leaders and shows you how to make them and use them.
Fly Fishing Rods
HERCULES Pre-Tied Loop Fly Fishing Leader 6 Pack with
DIY Fly Line Loop with Step-by-Step Instructions - Fly Fishing
Making loops, Global FlyFisher
Fly Fishing Rods
How to Tie a Perfection Loop Knot
How to tie the No-slip Loop Knot • FlyFish Circle
The Perfect Seven, Global FlyFisher
Three fly fishing loop knots; how to tie them and how to join them