Cogwheel



Cogwheels, also known as Tinker's Gears, are items that fit exclusively in Cogwheel sockets, much in the manner of cut gems. Currently the only items having Cogwheel sockets are Bio-Optic Killshades, Retinal Armors, and the Ghost Iron Dragonling, all crafted by engineers.

Source
Cogwheels during Cataclysm, which requires an engineering skill of 525 or higher to use, are sold by the following vendors:


 * in Stormwind City
 * in Ironforge
 * in The Exodar
 * in Darnassus
 * in Highbank, Twilight Highlands
 * in Undercity
 * in Thunder Bluff
 * in Orgrimmar
 * in Orgrimmar
 * in Silvermoon City
 * in Dragonmaw Port, Twilight Highlands

The Twilight Highlands vendors can only be accessed after completing a short chain of quests, which require level 84 or higher.

In Mists of Pandaria the cogwheels are crafted by the engineers themselves using Ghost Iron Bars (2).

Description
Currently, all Cogwheels are unique-equipped, preventing a person from doubling up on any of them.