Hardly used for two swim classes. From manufacturers selling page on Amazon- The FINIS Floating Fins increase leg strength and help athletes swim at faster speeds. With its long, hydrodynamic blade, the Floating Fins add propulsion to flutter and butterfly kick. Buoyancy from the fins lifts the legs to the surface reducing drag from the rest of the body. The Floating Fins' closed heel design provides protection against overflexion of the ankles and increases comfort. Great for all ages and all levels of swimming the Floating Fins are color-coded by size from the shoe size Junior 8 to Adult 14. Made of soft floatable rubber the Floating Fins will not sink in either fresh or salt water, making them ideal for open water and pool training. Features and Benefits Color-coded by size, check the size chart before purchasing The long blade is designed to increase leg strength and speed Buoyancy from the fins lifts legs to the surface, making it easier for swimmers to find correct body position Great for all ages and abilities; floats in fresh and salt water Made of a soft, natural rubber for increased comfort. Rinse in cool, non-chlorinated water after each use.