Close & Secure
Being able to close your pouches comes both pros and cons. It takes longer to reload and can also give you away as opening your pouch makes noise. On the other hand you rest assured that you won't lose any mags while playing and it will protect your mags from dirt and other debris that might cause malfunctions.
UNIVERSAL
There isn't much to say here, you can pretty much fit any AR mag in there.
HOW TO MOLLE
For some, it's straightforward, for others, it's something to learn.
Check out this gif to see how to molle your pouch perfectly in order to have it as safe and fixed as possible.