2-in-1 protection: This combination detector protects against both smoke and carbon monoxide Wireless connection: When one of the detectors sounds, all the sensors will be triggered too Built-in battery: This wireless detector has a lithium battery with a lifespan of 10 years and ...2-in-1 protection: This combination detector protects against both smoke and carbon monoxide Wireless connection: When one of the detectors sounds, all the sensors will be triggered too Built-in battery: This wireless detector has a lithium battery with a lifespan of 10 years and will issue a low battery notification Test/Silence button: A simple push of a button allows you to test or silence all detectors associated with the system Full Home Coverage: Connect up to 24 wireless smoke detectors, CO detectors and Link+ combo detectors for maximum home protection Easy to install: This smoke and CO alarm is easy to mount on any wall or ceiling using the included mounting hardware.