This is a light or beeping sound that lets you know that you've reached the monitor's range limit. If you have a model without this feature, static might be the only indication that you're out of range. (A monitor's range can vary due to your home's size, its construction materials, and other factors.) The greater the range, the better--especially if you plan to take your monitor outside.
As you'd expect, the talk-back functionality and audio quality on the VTech are great—easily better than the rudimentary talk-back features on our video monitor picks. With the battery lasting about 19 hours on a full charge, this monitor has the strongest battery life of any in our test. Rated to a range of 1,000 feet, it exceeds the range of our pick (700 feet) both as advertised and in practice during tests.
One minor distinction about the DXR-8 is that it comes with two interchangeable optical lenses (a standard lens and a zoom lens) and you can also buy a wide-angle lens. Having three different lens options is nice, but in practice we felt the zoom on the standard lens was sufficient, and we expect most buyers would probably not bother changing the lenses frequently, if ever.
Wireless encryption: This ensures that no one else can tap into your monitor’s “feed” and see what’s going on in your house. WiFi-enabled monitors are great for portability and range, but may be more susceptible to hacking. If you go this route, be sure to secure your home wireless network and keep the monitor’s firmware updated. Otherwise look for digital monitors with a 2.4 GHz FHSS wireless transmission.