The Offshore loop or Flemish eye is used to create a reinforced loop in a leader. It works well with monofilament or stainless steel cable.
To form an Offshore loop first thread a crimping sleeve on to the line. Then make an overhand knot in the line to form a loop, and pull it to the required size. Pass the line around the loop a second time and thread it back through the crimping sleeve. Using a crimping tool carefully swage the sleeve in place.
For added security when using heavy tackle you could use two sleeves and wrap or haywire twist the line around itself before swaging the second sleeve.