What makes a carbon monoxide detector 'smart'?

Smart CO detectors add wireless connectivity, typically Wi-Fi, Matter, or an app ecosystem like Ring or Kidde, so the alarm sends real-time push notifications to your phone even when you're away from home. Some models in this pool also offer wire-free interconnection so one triggered alarm sounds all of them. Note that several popular 'smart-adjacent' picks are actually plug-in units with digital displays and LED status lights rather than true app-connected devices, so read the listing carefully.