The Oceanic Viper Open Heel Fin uses a flexible duct built into the blade for more efficient capture and control water as it flows below the blade length during a kick cycle. Reinforcing bars on each side of the blade provide power, but are also shaped to prevent water from dispersing over the edge of the blade which could reduce the blade performance and output power. The blade itself uses a double material construction to create semi-rigid and completely flexible frames that allow the blade to form a U shape that directs water under the blade and from the tip to a more focused jet that improves thrust. This version of the Viper Fin has an open foot pocket for use, with neoprene or dry boots.