The Link2Home Wireless Chime simply plugs into any USB power supply and connects to your Link2Home doorbell over RF through the Link2Home Pro app (Free). It means you do not need to be near your doorbell or smart device when someone rings the doorbell. It has a discrete design, measuring just 60mm wide and 24mm deep, allowing the chime to blend into your environment. It emits a loud 120dB alert with the option to choose from 4 different melodies. The volume can be adjusted within the app screen. Simple and easy to set up with two button presses. Reset the chime with one button press and then sync with your doorbell with another button press on your doorbell device. System Requirements: Wi-Fi ConnectionMobile or tablet with iOS 8 or later, or Android 4.1 or laterLink2Home Pro Account (Free) Specification: Range: 20mAdditional Information:• Bell Type: Wi-Fi Chime• Colour: Black