ESP8266-12 Board with Battery Holder

The board can work on its own with Lua scripts, but you still need a USB to Serial adapter.
This board has the ESP-12 module with 4MB flash memory. You can put 3x AA batteries in the battery holder to let the module run completely independently.
In addition, there is an RGB LED, light sensor (resistor) and 6 other controllable LEDs on the module.

In addition, just like any other ESP8266 module you can put the Arduino core on it so you can use this board standalone with Arduino.
If you want to use the board as Arduino, start here.
The pinout is described in the one of the images. De light sensor is connected to the only ADC pin on the board.