Used for about 2 months. The condition is clean, and the operation has been confirmed. There are two batteries, one unopened and one almost new that was opened for operational check, for a total of two, which are included. Brand: Sense-U Material: Acrylonitrile Butadiene Styrene (ABS) Color: Blue Compatible Devices: Smartphones Screen Size: 0.96 inches Product Dimensions: 40mm length x 40mm width x 10mm height Know the movement of the baby's abdominal breathing: Unlike traditional video cameras and audio monitors, you can easily and safely monitor the movement of the baby's abdominal breathing, sleeping position, and body temperature using a smartphone. When the baby's movement is weak, the dedicated app terminal will sound an alert. Baby's rollover reminder: The Sense-U baby sensor monitors the baby's sleeping position in real-time and sounds an alarm on your smartphone when the baby is sleeping on their stomach. Protect your baby from overheating & cold reminders: When the temperature around the baby's abdomen is too high or too low, an alarm will sound on your smartphone. Uses low-power electromagnetic field radiation-free Bluetooth: Uses Bluetooth's ultra-low power technology, with low electromagnetic field radiation and is healthy (signal strength is equivalent to 1/1000th of a mobile phone), and the straight-line communication distance is 15 meters. When the device enters the effective communication range, it will automatically reconnect. By using the separately sold Sense-U base station, you can check the baby's condition from anywhere with voice and light notifications. It was a great help when I couldn't sleep due to anxiety until my child started moving and was able to roll over. It's simple to use, and the sensor is responsive. I hope those who are about to give birth or have a small baby will use it.