Uncraftable Mask of the Shaman
Normally usable in crafting, this item is uncraftable, also known as 'dirty'. For a short amount of time you could receive this item from the Mann Co. Package as uncraftable. This was a glitch because the weapon was never available in the Mann Co Store.
There is only 1 known instance of 'dirty' Mask of the Shaman.
The Mask of the Shaman
Team Fortress 2 Level 10 Mask
An invincibility mask made by the Ancients. It hasn't worked in a long, long time.
( Not Usable in Crafting )