Simply download the free app, plug the RemoteLync into an outlet, and it will listen for your existing smoke or carbon monoxide alarms. It uses patented technology to distinguish smoke and carbon monoxide alarms from background noise to reduce the chance of a nuisance alarm. Once an alarm goes off, RemoteLync uses your home’s WiFi to send an alert to your smartphone, which you can then decide to call a preprogrammed contact or 911. RemoteLync notifies homeowners of a home emergency when they're away – offering peace of mind at a great value. Ideal for a primary residence, vacation home or rental properties. Features: Choose to notify pre-selected contacts or 911 if alarm is detected Voice prompts help with installation and testing One RemoteLync unit will cover all alarms in an average-sized U.S. home Connects to your existing wireless router and sends messages via your home’s WiFi No monthly fees Free App compatible with devices running Android 4.1+ and iOS 6.0+ Dimensions: 2.25” W x 2.25” H x 2.25” D Compatible with any UL listed smoke or C/O alarm made after 1999