The Perfection Loop knot is designed to easily create a end loop in your leader or when you wish to connect your fly line and leader in a loop to loop connection. If you use a heavy butt section of mono and nail knot that section to your fly line, you can create a simple perfection loop in the mono section. Most pre-made leaders like Climax come already with a perfection loop in the butt section. Simply slip the leader loop through the mono butt loop and create a loop to loop connection easily without tying a knot (assuming you have a perfection loop on both ends)
Some complain that this loop to loop connection creates a slight hinge effect where the loop to loop connection is made and prefer to blood knot the mono butt section to the leader. I rarely experience this effect when using a stiff butt section made from Maxima or Mason leader material. - Jeff
The Fisherman's Ultimate Knot Guide
Don't ever forget how to tie that knot again! This 3 card set fits easily in a shirt pocket or tackle box and also folds out to a 12" ruler. Waterproof plastic cards feature clear illustrations of 10 most popular knots: Improved Clinch, Palomar Knot, Uni Knot, Surgeon's Knot, Double Uni Knot, Perfection Loop, Dropper Loop, Surgeon's End Loop. Nail Knot and Blood Knot.
Price: Only $4.50 delivered. Available - Order here