It's a magazine for your magazines.
Why?
What for?
What does it improve (except maybe a mall ninjas penis size)?
More info here (with some attempt at justification).
If it ain't broke, don't fix it.
Looks like a waste, all the way around.
It takes up way more space for 3 magazines than the old school ALICE 3-mag pouch and WAY more space than a chest rig or MOLLE pouch. . .
..... and let's not even think about the old "...but my magazine magazine jammed" excuses this thing sets up.
//rant off