Leader to tippet , seagauar knot. Over lap the leader and tippet Fold a large loop in both , insert your index finger into the loop stir (twist) the loop 3 times , reach thumb and index through the loop and pull through the tippet and tage end of leader. This is a very strong and fast knot that is good for fluorocabon or mono and is not sensitive to a difference in tippet and leader diameter.

Some saltwater guys call this knot simply a tippet knot