From Halopedia, the Halo wiki
Signal units are small Covenant devices used for communication. They are kept strapped to one's belt, and can be activated at the touch of a button.
The crew of the Rapid Conversion repeatedly used signal units to communicate with one another throughout the course of the First Battle of Harvest.
List of appearances
- Halo: Contact Harvest (First appearance)
- ^ Halo: Contact Harvest, page 197