Voice activated nano-ink is a form of nanotechnology used to ensure the identity of an individual. The tattoo is activated by a certain word or phrase, causing the special marking to appear on a certain area of the individual's body.
When Rex's old gang met Rex once again, Skwydd wanted to make sure that it was really him. Tuck told Rex to move up his sleeve, to reveal his wrist to them. When Tuck spoke the words "ink check", the markings appeared on his skin. When Rex questioned it, Tuck mentioned that it was Rex's idea and that they all had it for precautionary reasons, having trouble with a shapeshifter in the past.
- Tuck (right shoulder)
- Skwydd (underneath the tentacle that covers his left eye)
- Cricket (right side of the neck)
- Rex Salazar (underneath right forearm)