What is the difference betwween air alert 3 and air alert 4?

Question

And does air alert 3 really increase your vertical jump 8-14 inches in 15 weeks.
if you have tried it or know someone who has tell me their results.

Answer 1

the difference is dat the 4 one is like improved in some way some people had knee and back problem wit the 3 one so..yea and i had the 3rd one and they did increse my jump by 10 inches but i had some knee problems ma joints started hurting so get the 4th one or get jumpsoles but airalerts r betta.