The Summer Infant SecureSleep Audio Baby Monitor eases your mind by making sure that you always know whether your baby is comfortably sleeping or is awake and in need of your comfort. With a range of 650 feet, you'll always be able to keep one ear on the nursery while you work around the house or catch up on your own sleep. The monitor also acts as a soft glow nightlight for your baby, with an added convenience for you: the nightlight changes color based on the temperature of your nursery, letting you know if it's too hot or too cold. It transmits on low-interference 900 MHz with a secure and private digital signal.