•Onelink Smoke Detector and Carbon Monoxide Detector | Hardwired | First Alert•SMOKE + CO DETECTION 2-in-1 smart smoke and carbon monoxide alarm alerts you to both types of danger in your home, with a photoelectric smoke sensor and electrochemical carbon monoxide sensor•MOBILE + VOICE ALERTS Alarm sends emergency notifications, via your phone, while voice alerts tell you the type and location of danger•A HOME SAFETY NETWORK + ALEXA Interconnects with other Onelink devices (sold separately) to create a smart home safety network, so if one alarm sounds, all will; works with Amazon Alexa so you can ask Alexa to check the status of your Onelink alarm (Alexa device sold separately)•EASY BATTERY CHANGES Easy-access battery door, for simple battery changes; replaceable 5-year battery•COMPATIBILITY Compatible with Apple HomeKit; can be used on both Apple and Android devices•INTERCONNECTIVITY: Unlike other smart combo alarms, Onelink can connect with any other hardwired alarms in your home (including First Alert and non-First Alert brands), and can send a mobile notification for any detected emergency, keeping your whole home safe and connected