Soft Sup Center Fins are crafted from PVC material for a flexible, durable design that delivers long lasting performance and reliable use. Compatibility and installation These fins fit standard longboard fin boxes, enabling easy installation and a secure fit. They are designed to enhance the performance and stability of your longboard, providing an exceptional surfing experience. Performance and handling Ideal for river running, these fins support both experienced surfers and beginners. Their streamlined design and flexible structure allow for smooth navigation through rivers, with control and maneuverability. Use scenarios River running on calm to moderate currents where precise tracking and steering are beneficial. Learning and practicing balance on smooth water to improve stability and turning with a centered fin. Upgrading an older longboard for improved stability and reliability during recreational sessions on lakes or slowmoving rivers. Sizing and fit One size fits standard longboard fin boxes.