Kick your swim level up using Finis Positive Drive Fins. The Positive Drive Fins, PDF, have a unique, short and wide blade to help you kick properly for all swimming styles, even the Breaststroke. They also promote a natural supination kick. The closed toe construction provide maximum energy transfer from the leg to foot, thus increasing leg strength and foot speed. Feet feel comfortable in its ergonomic footpocket with a heel strap to secure them in, which allows the feet to flex more naturally.