Swimming with Zip VX Fins has many benefits including increased cardiovascular conditioning and ankle flexibility. The Zip VX leverages the energy created by the fins movement through the water to produce a springboard effect that boosts swimming efficiency ensures proper body position and increases thrust. ? Leverages natural kicking motion: boosts efficiency. ? Hole in the blade: increased thrust. ? Narrow blade: improves kicking mechanics and reduces fatigue. ? Easy-adjust buckles: custom fit. ? Non-slip pads on fin rails: provide traction for a better push off the wall.