Knock knock? Who’s there? Ring Video Doorbell, the world’s first battery-operated, WiFi enabled, HD video doorbell. See who’s a knocking, well, ringing, at your door from anywhere in the world thanks to live streaming via an app, along with other funky features such as motion sensors and auto cloud storage. It’s a cinch to set up, syncs in minutes and sports a built-in battery for power, or use your existing doorbell wires.