Used Scubapro Twin Jet AdjustableSplit fins are fast and maneuverable, keeping the fins within your body's slipstream and using a relaxed flutter kick. This allows you to cover a lot of ground without cramping leg muscles or straining ankles, resulting in a more enjoyable time underwater. The TWIN JET provides maximum propulsion with minimum effort. Its distinctive split hydrofoil shape allows water to flow between and around each blade, flexing independently to produce propulsion.