Product Description The Angelcare movement and sound monitor offers both sound and movement monitoring in one device. With a range of up to 820 feet and eight channels to minimize interference, the monitor offers continuous or voice-activated sound transmission and will sound an alarm when no movement is detected for 20 seconds. For convenience, the monitor features a temperature display and sound and movement indicator lights. From the Manufacturer This award-winning baby movement & sound monitor system is both pretty and practical. Slide the Sensor Pad under the crib mattress and its motion detectors will pick up the slightest movements; whether baby is sound asleep or wide awake. Plus, like music to your ears, you’ll hear every little sound coming from baby’s room on your portable Parent Unit, which features a full color digital display, nursery temperature display and other extras designed to give you the peace of mind you need to get a good night’s sleep too. Sweet dreams everyone! *Note: The Sensor Pad can be used with a regulatory standard baby mattress, whatever the size or thickness. However, it cannot be used with memory foam mattresses, dual sided, mattresses with a hollow frame or Purflo mattresses.