The nail knot is one of the best knots to use when having to join two lines of different diameters, such as leader or backing to the fly line.

When this happens, you will want a nail-knot tool. It makes the whole process so much easier, and it's a small, portable tool that you can just throw in your fly fishing pack until it is needed.

And he never hits the open water without his nail-knot tool. This simple device helps tie two tricky, yet essential, fishing knots: the nail knot and the nail-knot splice.

The Nail Knot Tool It wasn't long ago that a nail-knot was a required knot to learn in fly fishing. It was the knot you used to attach your fly line to the backing and to the leader. Today's fly ...