This 9’ Race paddle board Fin (fin screw included) fits all Atoll inflatable stand up paddle boards as well as any other paddle board with a US style fin box. If your paddle board, inflatable or hard board has a Universal Fin box, this race fin will fit. This fin enables better tracking with your paddle boards due to its length and promotes a faster ride. Tracking is the most important thing to keep in mind while on a paddle board. Tracking means: traveling from point A to point B with the shortest distance in between. This 9 inch SUP race fin allows for greater tracking via physics. Don’™t worry if you don’™t own an Atoll, if you have any other brand of paddle board with a US fin box, this fin will fit your paddle board. Knowing your terrain is the number one thing to keep in mind when paddling. What are the water conditions? For recreational paddling on lakes the standard 8 inch Atoll fin is adequate. But if it is speed, and breaking personal records you are after, make sure you use the 9 inch race fin.