Never heard of Alpha Sky. That is obviously a fancied up "eggbeater' omnidirectional antenna. I don't like the looks of the large surface areas. That is going to catch a lot of wind and get beat up on a car.
M2 Antennas makes a more conventional eggbeater, link above. They have a very strong reputation for quality antennas.
It is easy to build your own eggbeater with little cost. Plans are in the ARRL Antenna book.