Wireless Interconnect - Proprietary radio signal joins multiple alarms together, so when one alarm sounds they all sound. Voice Notifications - Unit verbally announces "Fire!", "Carbon Monoxide" and other alerts such as "Replace Alarm," which helps the user better understand current status of the unit. Alarm Locate Feature - Quickly find initiating alarm by silencing other alarms in the network. Photoelectric Sensor - Smoke alarm contains advanced photoelectric sensor that may detect visible particles (associated with smoldering fires) sooner than ionization alarms.