WF502 Wifi Temperature Sensor. Is a WiFi temperature sensor based on IOT technology . It can be widely used in refrigerators, catering, warehouse and HACCP system industries and so on. It can real-time uploading data to cloud via WiFi. Users can remotely view, monitor, and manage data online via any web browser. At the same time, the device also with flash memory to storage 20,000 temperature recordings. And it can generate PDF report via the USB port. With a built-in rechargeable lithium backup battery that can provide real-time data uploading and alarm notifications continously even after power supply cut-off.