What is the Exceedingly Rare Special item?

What is the Exceedingly Rare Special item?

So a recent update made CS:Go into a similar model to Dota2 and TF2.
As such, one of the weapon crates lists:
eSports 2013 Case
Counter-Strike: Global Offensive
Counter-Strike: Global Offensive
Base Grade Weapon Case
Case Series #2
This case contains one of the following:
M4A4 | Faded Zebra
MAG-7 | Memento
FAMAS | Doomkitty
Galil AR | Orange DDPAT
Sawed-Off | Orange DDPAT
P250 | Splash
AK-47 | Red Laminate
AWP | BOOM
P90 | Death by Kitty
or an Exceedingly Rare Special Item
So what is this Exceedingly Rare Special Item? Is it like TF2, where hats
would be uncrated with the Unusual particle effect, and do weapons get
that too? Or is it something else entirely?