Designed for top speed on a reach. The profile thickness and the profile length (cord length) are kept at their minimum, resulting in least drag and optimum downwind speed.
With good twist they provide excellent control at top speed.
The profile with the wide point slightly further back produces less drag and creates even lift throughout the whole wind range.
The constant twist and flex makes the fin very predictable and provides amazing control and top speed without lifting the nose out of the water.