Why is this device only available in AC/ Hardwire version?

The Onelink Safe & Sound is an AC powered only device, that uses your homes hardwired electrical circuit. You should position it where your current smoke alarm junction box is. Remove your current alarm and bracket and install the Onelink Safe & Sound. The app will guide you through the process. Included with the Onelink Safe & Sound are easy adaptor plugs, so you do not have to rewire to install your alarm. Since the Onelink Safe & Sound also works as a premium speaker, it uses your ceiling as an acoustic backdrop to fill the room with immersive, crisp omni-directional audio. The device works with Wi-Fi and has Alexa enabled functionality built in, so your home’s hardwired electrical circuit is needed as the device would use up much too battery power.

First Alert offers numerous replaceable battery and 10-year sealed battery alarm options. For more information, visit firstalert.com.