2.4GHz digital wireless transmission, stable transmission signal. *Built-in microphone and speaker for two-way audio monitoring. * High sensitivity, easy to hear crying, light on to alert parents. * Easy to pair, plug and play. * Place the transmitter at a distance of about 1.5 to 2.0 meters from the baby. * Maternal and infant units can be powered by 5V DC or 3*1.5V AAA batteries. * Volume adjustment * Two-way intercom, supports data encryption * Both receivers have built-in microphones and speakers * Transmission range in open space up to 250M Baby weight: 350g Packing size: 235* 135*55mm Packing quantity: 20 Packing weight: 7.75kg Packing size: 48*28*27cm