For parents of preemies and babies at greater risk of developing SIDS, the Angelcare Movement Sensor is a lifesaverâliterally. A sensor pad goes under babyâs mattress and detects babyâs slightest movements, even if he is sleeping soundly. If the sensor does not pick up any movement for 20 seconds, an alarm sounds over the two portable receivers and alerts parents. Along with the sensor is a traditional baby monitor that transmits all sound from the nursery to the two receivers. The receivers have a range of up to 200 feet and have light indicators that correspond with the noise level. The monitor and receivers have two channels and low battery indicator lights. Each unit can operate either by four "AAA" batteries or AC adapter (two included). This full-spectrum monitoring system is the recipient of numerous awards and is covered by a one-year limited warranty.