It stands for nuclear, biological, and chemical. It's widely used in the military. It is completely water proof, airtight, but its HOT! I have a scentlok hood and pants, but i have an x system long sleeve camo shirt and base layer pants.

The silver thing is not meant totrap in human odor, and not let it escape, like carbon is. It is designed so that odor causing bacteria cannot grow on your clothes, but your body odor can still escape.