Skins — Wiki

Premium weapon skins: pick a look for each weapon on the website, and it goes on your weapons in game.

Premium players pick a skin for each weapon in the website's Armory, and the server puts it on their weapons in game. The skins are the game's own: the Armory shows each one's market picture, and turns it round in 3D.

Each skin is kept in its best condition (Flawless), as are the default looks and the skins that come in only one.