Attunement: Homebrew rules.

Attunement:
Attunement is a hidden statistic used to determine someone’s ability to use certain magical items and use cybernetic augmentations. Every character has a base attunement of 3 but can gain an additional attunement slot at constitution levels 14, 18, and 20 for a maximum of 6 attunement. Constitution provided by items does not increase your attunement.
Different items and cyberware cost different amounts of attunement to properly equip and you can never fall below 0 attunement.
Monks, Pugilists, or other classes re-skinned to be cyborgs do not have to pay for their base cyberware through attunement.