More details about the The Dropper Loop
Uses: The Dropper Loop creates a loop which stands out at right angles to the middle of a length of line It can be used in your leader or tippet to provide an extra attachment point for an additional fly. If desired the loop can be made long enough to set a hook directly on it. However, this Dropper loop should not be too long to minimize the risk of fouling and twisting. The Dropper knot is also used on multi-hook fishing lines.
Tying it: There are two main methods of tying it. The animation above shows the loop being wrapped round the overlap point which is held still with your fingers.
Alternative: The same result can be obtained by keeping the loop still and passing a match-stick through the overlap which then is used to twist the overlap into a spiral. The loop is then passed through the hole occupied by the match-stick.
Whichever method is used, the knot should appear almost symmetrical either side of the loop.
Advantages: The Dropper Loop angles away from the line which helps to avoid tangles.