Does it help more if you have several pieces or is 1 enough to stay hidden? It's the one that makes you stealth when you don't move and is crouching...

you mean shadowed armor? or is there actually a set called 'chameleon armor'?

It's a legendary "enemies have a harder time detecting you, while you're sneaking and not moving" ... Makes you stealthy, perfect for sniper

It's not a set tho, piece by piece