This is one of the easiest and quickest loops to tie, creating a non-slip loop in almost any size line. It is also extremely strong, retaining 100% of line strength. This loop can be used for larger streamers, to allow more action especially when using heavier leader. Another use for a loop is to create a quick attachment between lines. Many tapered leaders these days have a loop for quick rigging, and having a loop on the end of a piece of monofilament attached to your fly line will allow you to change your leader without tying knots.
Step 1: double back the desired length of standing line
Step 2: tie an overhand knot in the doubled line
Step 3: pass the loop through the knot again (a double overhand knot)
Step 4: slowly pull the knot tight, maintaining the desired loop size, trim tag end