Operation Steel Wave brings attachments to R6 - a new category of skins. Attachments are what you equip on your weapon - optics, grips, barrel and underbarrel. Skins apply to the whole set, meaning you can't apply one skin to a barrel and another to your grip.
There's only a few attachments skins so far, which you can see here.
And talking of attachments...
There's big rumours flying around that Ubi will rework the optics system, adding x1.5, x2, and x3 optics, and tweaking who gets access to the ACOG, but nothing's been confirmed.