Deadman Wonderland Collars, Necklaces, collars or dog collars, were neck shackles for prisoners on a death row in Deadman Wonderland prison. The necklaces were used for tagging death row inmates. They have a tracking system installed inside of them which can track a prisoner if they try to escape. The collars carry a lethal poison inside of them that is injected into the carriers jugular veins, which kills them within three days. Unlike regular prisons, death row inmates can purchase a temporary antidote that resembles a piece of candy using Cast Points. The necklace also has a timer which has a countdown from 72 hours since the last antidote intake. If the prisoner does not take the medicine every three days, their body will stop functioning and will result in a painful death. This data can be accessed by the prison warden. When the prisoner is near death, a red light on the necklace will begin to blink and beep, warning the prisoner that they're near death. When the countdown ends, the necklace will display "DEAD" and kills the prisoner. After, it detaches itself and displays "UNLOCK". The necklace can also be unlocked by a special key.
When the truth about Deadman Wonderland was discovered, all prisoners had their necklaces removed.