Package Includes:
Size: 34mm x 25mm x 6mm
WeMos D1 Mini clone ESP8226 ESP12F 4M Bytes wifi Development Board Module. The module comes with 6 rows of header pins that can be soldered on to use the module with D1 mini shields.
Techical details:
These modules use a CH340G serial chip for programing. They can be programmed with the Arduino IDE, micropython, lua, ESPEASY, nodemcu flasher etc etc.
To use these board with the Arduino IDE you'll need to add ESP8266 boards to the Arduino IDE boards manager. Here is a tutorial that someone has made on youtube that shows how this is done.