Equipment Mods are the product of Research and Development. These items, once slotted into the socket of an equipment piece, will provide a bonus to one or two stats. They are classified in 6 different colors, while sockets are classified in 3 different colors. Socketed items are not tradeable although they could still be sold to vendors.
If the color of the mod is compatible with the color of the slot the mod is put in, the mod will provide and additional socket affinity bonus which boost the stats further.
Most equipment except trinkets, weapons, neck or face items could be socketed. Players could override the original equipment mod by adding another one, although the original would be lost if not salvaged by using a recovery kit.
Stats from equipment mods are shown separately on the tooltip. "20 [+4]" means the item originally has 20 in this stat and the mod adds 4, resulting in the total of 24. This addition does not show up in comparisons. If this socketed item is moused over when a non-socketed item with 25 in the stat occupies the slot, it would show -5 instead of -1.
Certain tiers of equipment mods may also be available from PvP vendors (prefab mods).