The Chroma 2 Case is a weapon case consisting of 15 community-made weapon skins released as part of the April 15, 2015 update. It requires a Chroma 2 Case Key to be opened.
On the Galil AR | Eco, a small barcode can be seen with the numbers "000007355608" written under it, and 7355608 is the C4 code.
On the MAC-10 | Neon Rider, a poison hazard symbol is hidden on the magazine, normally obscured by the magazine well, and can be seen for a very brief moment when reloading.
On the Five-SeveN | Monkey Business, its magazine has the word "NOM" written on it.