Through the iPhone app, the Onelink Smoke Alarm is able to test the viability of a smoke detector, notify users when an alarm goes off while they're away, and silence alarms that have been set off accidentally. It's also able to toggle a built-in nightlight (hardwire version only) on and off and each connected alarm will go off whenever one detects something harmful, directing users towards the problem with voice alerts.
With HomeKit integration, users can ask Siri to dim the nightlight or check for smoke or carbon monoxide alerts. The Onelink Smoke Alarm comes with a built-in battery that cannot be replaced and lasts for 10 years, putting an end to low battery alerts in home smoke alarms. There's also a hardwire version with a battery backup.
The Onelink Smoke Alarm works over Wi-Fi and Bluetooth, and does not require a central hub. According to The Verge, First Alert will be introducing additional HomeKit-enabled devices in 2016, including a safe and a combo carbon monoxide, temperature, and humidity sensor.
The battery-powered Onelink Smoke Alarm is priced at $109 and does not include a nightlight feature, while the hardwired version with a nightlight is priced at $119. The Onelink Smoke Alarm can currently be purchased from the Lowe's website and will later be available on Amazon and in Apple retail stores.
Update: Apple is now selling both the hardwired Onelink Smoke Alarm and the Wi-Fi Onelink Smoke Alarm in its online store.