The 20cm US-box fin is designed to fit the centre fin box of :
ACS - 8'4" & 8'4" Wahine
boards come equipped with this fin.
Fins are an integral part of any surfboard and the better you become as a surfer the more notice you should take of your fins. They are literally your driving force through the water. At least 20% of your board’s performance is dependant on what sort of fins you’re using and the method by which they are connected to your board.