Mk refers to the quality level of Items, [Components], Cyberware, [Mods], and other objects.
The Mk of an Item, [Component], Cyberware, or [Mod] determines the effects you recieve as well as the Value and Upkeep costs you must pay when purchasing and using them.
Example: Purchasing a Mk.1 Heavy Specialised Jobber would cost 500 [Credits] with an Upkeep of 20 [Credits]. It would also offer a bonus of 2 to a specified Skill Check or Attack. Whereas Purchasing a Mk.2 Heavy Specialised Jobber would cost 8,000 [Credits] with an Upkeep of 40 [Credits]. But it would offer a bonus of 4 to a specified Skill Check or Attack instead.
You can raise the Mk of Items, [Components], Cyberware, or [Mods] by Augmenting them as described below.