Easy to Install: The sensor and receiver are paired already, all you need to do is attach the transmitter, plug the receiver into any standard outlet, pick a tone you like and here we go. Built to Last: With one standard household AAA battery in equipment and design of Ultra-Low-Power, the sensor can easily last 1-2 years. which allows battery to be replaced less often, save your time and money. A Must-Have: 500FT reliable long working range, perfect entry alert chime when door opens for home and business. What about insecure front door, child safety gate, upstairs window, cabinet, basement door...you tell me. Mute to 120dB: 58 unique long and short tones with 5 adjustable volume levels. The max volume 120dB is loud enough to be heard anywhere in the house, you will never miss out an alert. Prefer not to be disturbed? Set it to mute. Reliable After-sales: One Year Warranty & Lifetime Friendly Service. We started to make security products since 2004, so we have confidence on the quality of every sold unit. We will never let you down, grab your door dinger now! METAK Wireless Door Chime, Door Open Contact Sensor Alarm with 500 FT Range, 58 Chimes and 5 Volume Levels for Business/Store/Home/Office When Entering, 1 Transmitter + 1 Plug-in Receiver White