The Alecto DBX-85 ECO uses DECT technology, making it 100% interference-free. The microphone sensitivity is adjustable in 5 steps. You decide how much sound you want to hear. In addition, a number of LED lights will automatically light up as soon as sound is heard. Lights light up when there is no range or when the battery is empty. To appease the little one during a cry, you can speak to the baby through the parent unit.A baby monitor with battery is like a smartphone that runs empty when you are playing a movie. The battery life is limited.