Whether you are getting in shape doing laps at the pool, or in open water, body surfing at the beach, or taking a snorkel on a tropical reef, these power efficient rubber swim fin design is one great choice. Long fin blade translates the lightest kick into a forward thrust. If you need to wear them for long periods of time the soft orthopedic foot pockets will be comfortable for any extended workout. Size indicates color of fin foot pocket. 100% natural rubber is very flexible, so the fins feel like a natural extension of the foot while providing a snug but comfortable fit. Long blade provides extra power and force. Helps to elongate the kick and improve technique and speed. Great for all levels of training, teaching, and recreation.