A powerful fin by nature. The special center channel, which is designed to flow more water backward, gives you more speed and power, allowing you to come on top of the conditions. The angle of the blade (from horizon) is designed with efficiency in mind. As the down stroke begins, the fin will provide more than sufficient propulsion without straining. Size L/X can be used with size 9 ~ 12 boots and size S/M can be used with size 5 ~ 8 boots. Rubber grip under foot pocket prevents slipping on deck or similar surfaces. Underside foot pocket drain hole for better water clearance.