1. On-board mature and stable ESP-12F wifi module, -capacity 4m bytes flash memory; 2. The I/O port of the WIFI module and the UART download port are all led out to facilitate secondary development; 3. The power supply mode supports DC7-28V / 5v; 4. The first reset button of the wifi module on the board; 5. ESP-12F supports the use of development tools such as / for ide, and provides reference programs in the for development environment; 6. There are 4 5v relays on the board, which are used to switch output signals and are suitable for controlling loads whose working voltage is in the AC range. 7. Onboard power indicator and relay indicator. Power supply: 8 channel: DC5V/7-28V Writing mouth: The GND, , TX, and 5V of ESP8266 are connected to the GND, TX, , and 5V of the external TTL serial port module respectively. The IO0 should be connected to the GND when the download is complete. Disconnect the IO0 and GND after the download is complete. Relay output: NC: normally closed end, short connect with relay closing, suspended after closing; : public terminal; NO: normal , the relay is suspended closing, and short connected with after closing. Colour:green+blue Material:PCB+electronic components Size: 93 x 87mm Package Contents: 1 x ESP8266 Wireless WIFI Relay Module Only the above package content, other are not included. Note: Light reflection and different displays may cause the color of the item in the a little different from the real . The measurement allowed is +/- 1-3cm.