What's the best product for improving your vertical leap?

I just started going to the gym and i just focus on running, chin-ups, and cycling. If your not over 18 i wouldnt do any weights, it just damages your muscles the best way is lifting your own body weight (chin-ups) that doesnt do any harm.

I plan on doing air alert again over the summer as i wanna get better at blocking rebounds.

umm...high schools have weight rooms for a reason...

the fact on weightlifting is you can start at any age, you just cant go heavy until your about 15-16, at which point you can start doing some heavier power programs.

When you do weight training, try to implement explosiveness into the lift. I work out at a gym run by Peter Twist, who is the strength and conditioning coach for the Vancouevr Canucks (NHL team), and so we get a lot of 'explosiveness' exercises. Something really simple is to just change up how you do squats. Go down slow (for a 3 count or so), and make sure you're sticking your butt out and not letting your knees go way ahead of your feet. Then shoot up fast and go right up on to your toes. Just making adjustments like that to many exercises can do wonders. And for core training make use of a bosu. Doing some free weight stuff while balancing on one of those works the core nicely.

I'm actually using Air Alert 3, it's pretty hard to do it everyday, but once you get used to it it's fantastic. I find myself a better jumper right now, still a month left.

anywhere i can get the air alert program for free?

Search deep into Google. Theres a few sites, I don't have a link but I wanna start it late December so i'l probably be keeping an eye out

anywhere i can get the air alert program for free?

I'm not sure if mixmakers.net is still online, but I saw a guy posted a video and .pdf for Air Alert few months ago... You should check there.
Anyway, imo the safest way to increase your vertical is jumping rope, stretching and "keep jumping (reaching a target, like the backboard or rim)"!