The Positive Drive Fins (PDF’s) use a unique ellipsoidal blade to generate correct propulsion in all swim strokes. Traditionally fins are not made for Breaststroke, but the asymmetrical shape and adjustable heel strap allows the swimmer to safely build power in the Breaststroke kick. The short and wide blade design also promotes a natural inward supination kick style for Backstroke, Butterfly, and Freestyle. The PDF’s use an ergonomic footpocket to comfortably place the feet in the ideal swimming position, and the heel strap to secure the fin, allowing the feet to flex more naturally. A closed-toe construction provides superior energy transfer from the leg to the foot. The PDF’s will increase leg strength, foot speed, and ankle flexibility for all four competitive swim strokes, making the fins great for training the Individual Medley event. Available in multiple sizes for a custom fit.