Ringing Ceders

There are a lot of Vertical Jump Programs out there, for someone that would like to increase their leaping ability.  They have names like: Dunk now, Air alert, and Jump manual just to name a few.  How does one know which program to use or at least try?  There are a few factors to consider when making this choice.  Do you have the extra equipment or facilities that may be needed to completely do the program.  Also, cost is always one of the factors to consider.  Ultimately, the biggest question to ask is, does it work?  For answers on the programs success read as many reviews as possible.