This is an E-Ink raw display, 4.2inch, 400x300 resolution, with embedded controller, communicating via SPI interface, supports red, black, and white three-color display.
Due to the advantages like ultra low power consumption, wide viewing angle, clear display without electricity, it is an ideal choice for applications such as shelf label, industrial instrument, and so on.
No backlight, keeps displaying last content for a long time even when power down
Ultra low power consumption, basically power is only required for refreshing
Comes with development resources and manual (driver board schematic, examples for Raspberry Pi/Arduino/STM32)
To fastly get started with these raw displays, please consider the following driver board: e-Paper ESP8266 Driver Board
The driver board of 2.7inch E-Ink display HAT can also be used for testing the 4.2 inch E-Ink raw display, here's the Wiki for your reference.