Expand your Ring Alarm system to secure each door and window in your home, and hear chirps as soon as they open. Ring Alarm Contact Sensors mount to any door or window frame in your home for easy, DIY installation. Connect them to your Ring Alarm and receive mobile alerts from the Ring App so you’ll always be the first to know when something’s ajar. | Ring | | Alarm Contact Sensor (2nd Gen) (1-Pack | White | Best Buy