Made by Aqua Sphere – a brand which targets triathletes and fitness swimmers – the Zip Fin (now the Zip VX Fin) performs like an athlete itself. It’s blade features an interesting, non-traditional design which allows for more intense lower body workouts without over-extending your ankles.
The foot pockets are made from rubber which allows for the most comfortable fit. (I always prefer rubber foot pockets over silicone). Also, the heel on this fin is not enclosed. Instead, there is a comfortable, neoprene-covered, adjustable heel strap featuring pull tab adjustment buckles. The heel strap is also replaceable if it ever wears out.
One of the most unique features of the Aqua Sphere Zip Fin is its split bade design coupled with its “Nature’s Wing” technology. The fin actually functions more like a hydrodynamic sea creature’s fin rather than a traditional swim training fin. When you first start kicking with this fin, you can definitely feel the power behind the technology. The split blade seems to stabilize the fin in the water, keeping it from moving laterally and thus, reducing ankle fatigue. Aqua Sphere claims that a reduction in ankle strain will result in an ability to engage the entire leg and work out for far longer than would be possible in a more standard fin.
Just like the Speedo Optimus, it seems like the Zip Fin requires less power for a greater return. I’m not sure exactly how the system works, but the Aqua Sphere Zip Fin seems to flex naturally and fluidly in the water. Imagine a manatee’s flipper fluttering through the current. That’s exactly how this fin feels. Although the fin blade itself is made of plastic, there are rubber channels throughout which allow the blade to flex at multiple points – making it a very comfortable flutter kicking fin. The squareness of the blade disallows breaststroke kicking, but dolphin and flutter work beautifully.
The Zip Fin is available in sizes S-L.