The baby monitor uses a high-performance sensor built into the panel to detect the baby's movements, including breathing. It accurately detects the baby's movements during sleep, and if no movement is detected for 20 seconds, an alarm will sound. It prepares for emergencies such as SIDS, falls, and suffocation. I purchased it and used it a few times, but I no longer have a need for it, so I am selling it. There are no scratches or stains. Operation has been confirmed.