I have a door sensor already which works well. But I have been moving all of my security bits and bobs to Ring as I really like their stuff. It just works and is very good. However, what surprised me (and I admit it does say it in the blurb) is that you have to have the alarm base station for it to work. All I wanted really was a notification to my phone / ring app when it goes off and potential then to trigger something via Alexa; however, it cannot do this. Seems a very basic feature when compared with my existing sensor which I am still using.