4.6″ Flexi SUP River Fin Included with our 12’6 and 13′ AllWater Touring Paddle Board Packages but also available to buy separately. The Quroc 4.6″ Flexi River Fin is ideal for paddling rivers with shallow sections. The Quroc 4.6 inch River Flex Fin (fin screw included) is an essential addition to your inflatable stand up paddle board. The fin fits a US or “Universal” fin box and the bottom edge of the fin measures 7″. Great for kids and those with a smaller board, the river fin allows the rider full safety when paddling in shallow water or when the tide is low. The fin is included with both our 13′ and 12’6 All Water Touring Board packages, the Flexi SUP River Fin is also available to buy separately. Why choose our 4.6’ Flexi SUP River Fin? Our 4.6’ Flexi SUP River Fin is the perfect shallow water solution The fin is ideal for those planning to be paddling in shallow waters. The flexi element of the fin means you don’t have to worry about hitting rocks and damaging your fin boxes and board. The fin is specifically designed to flex and be used in shallow water conditions.