Characters wear interface rings to make phone calls, send messages, request items, play music, and do all manner of other tasks. Like a smartphone, these rings can also be used to track the wearer. In the early parts of the novel, these rings represent connectivity and accessibility. When wearing the ring, a person can have their needs met and socialize with those they care about. However, the rings gradually take on a more sinister meaning, as those in charge of society can use them to listen in on conversations and follow a person’s movements. The surveillance nature of the rings shows the power of those in charge of society—particularly the Specials.

The introduction of interface cuffs, which are physically fixed to Zane and Tally and cannot be removed, further reinforces the power of those in control. These cuffs make it possible to monitor all movements and words. Unyielding and omnipresent, the cuffs come to represent the totalitarian society they live in. Tally and Zane only become free of them as they prepare to also forgo society. They leave their cuffs, and the accompanying Crims leave their rings behind when they cast off societal expectations and join the New Smoke rebellion.