Aqua Sphere Alpha Fins are unique in that they are constructed entirely of EVA foam. EVA is soft and pliable, and there’s a lot of flexibility to the fin when compared to traditional fins made of semi-hard rubbers or plastics.
The EVA foam makes Alpha Fins positively buoyant, which means they float when placed in the water, rather than sink like other plastic and certain rubber fins. The bottom of the Alpha Fin, near the opening where your toes sit, has two small holes in it to allow water to drain out easily. This is definitely a plus, since moisture left over in the foot pocket would otherwise grow mold. Allowing for water drainage as well as air flow is a simple design feature that helps these fins last much longer than fins constructed without such vents. The holes are small enough that they don’t have any effect on the resistance created by the fins, and you don’t notice the vents when swimming with them.
The physical design is also unique to this model of fin. Rather than a squared-off blade like most fins, the Alpha Fins feature a curved profile, that according to Aqua Sphere, the manufacturer, allows the swimmer to perform a breast stroke kick while wearing them. Normally, a whip kick is impossible or cumbersome with traditional flat blade fins, since traditional fins are meant for a flutter kick either slowly while scuba diving or a faster flutter for cardio and swim training. I found that these were “ok” at breast stroke, and somewhat awkward for flutter kick. I do know of people who swear by these though, so you’ll really need to try them out yourself and decide if you like them. (Make sure you rinse them off when you’re done swimming and don’t walk on the bottom and you won’t have a problem). See Caring For Your Fins on the main page for more on basic care to make your fins last longer.
The alpha fin features an open heel design, similar to a strap on fin, except the “strap” part is not detachable – it’s moulded onto the fin. You put your foot all the way into the foot pocket, and then pull the ‘strap’ up and over your heel. I found the fit to be very snug, and that’s important when choosing a fin. You want to get a good transfer of power from your leg to the fin (loose fitting fins are less efficient). Please see the Proper Fit section under Choosing the Right Fins for more on why this is the case.
To sum up, this is certainly a unique fin design and one that you’ll really need to try out yourself to determine how they’ll work for your swim routine.