Features: 2.4GHz digital wireless transmission, stable transmission signal. Built-in MIC and speaker for one-way audio monitoring, with nightlight function. High sensitivity, the crying voice is easy to be heard and to inform parents. Adopt frequency hopping spread spectrun (FHSS), Anti-interference and sound clarity Position the transmitter at a distance of about 1.5-2.0 meters from the baby. Open space transmission range up to 250M. Specifications: Transmission Frequency: Ism 2400-2480MHz Transmission Power: 17dBm Modulation Type: FSK Power Supply: Built-in lithium battery Operating Temperature range: -10~+60 Storage Temperature: -40~+70 Material: plastic Baby Unit: 13 * 9.7 * 3.5cm Parent Unit: 13 * 9.7 * 3.5cm Package Size: 14 * 10.5 * 10cm / 5.5 * 4.1 * 3.9in Package Weight: 212g / 7.5oz Package List: 1 * Transmitter 1 * Receiver 2 * Power Cable 1 * User Manual (English)