It consists of two types of robots, the Grigos and the Bubs.
The Grigos are spherical floating robots with a single eye that can change colors depending on their status. They speak in a monotone, high pitched voice similar to a child or woman, and attack with electricity. Their function is to detect Nevi entering the city as well as any other crime that may be committed.
Flower-shaped floating robots that absorb the gravitational energy from gravity storms to stop them. Unbeknownst to everyone, they were actually storing the energy and are able to regurgitate it to shield the Angels.