The Roost™ Smart Battery – Alarm notifications delivered to you, wherever you are. This is not your average 9V battery. Our retrofit approach to the Smart, Connected Home is different. It’s affordable – you don’t need to buy expensive new devices. In fact, you just use your existing smoke or carbon monoxide detector. It’s simple to install. No hubs, no wires and no need to hire an outside contractor. With one smart battery and an app, Roost delivers peace of mind.