Sold as a Single Fin. Fits the Wilderness Systems Kaos and Dagger Koas surf kayaks (same boat!). The Koas typically takes one large fin (skeg) in the center and two small fins (skegs) on the sides. Fins can be used in any combination you see fit. It is assumed that these fins may fit the Wilderness Systems Alamax sit-in surf kayak. Fin depth is 2 9/16 inches. Fits a 9 1/16 inch long skeg box, screw holes are 8 3/16 inches on center. Includes two brass machine screws. (Stainless steel is not recommended but can be used.) The addition of a skeg adds performance, increases the ability of the kayak to hold position while trimming along the wave face and aids in tracking. Surfing the Kaos without fins allows for 360 spins. See Kaos Surf Video. Fins can be damaged in by shallows, reefs, rocks and in white water rivers. Instructions are included. (Formerly part number CNF-8025408)