This Module has another name: Gert-VGA-adapter, or Passive VGA adapter 666 for Raspberry Pi A+/B+/2B/3B/Zero The Raspberry Pi has an HDMI port to connect a display. If your monitor only has VGA, you have to use an adapter. Because this requires a digital-to-analogue conversion, those adapters can be quite pricey, and they can draw lots of power. As well as just allowing you to connect a VGA monitor natively. And unlike composite video, the DPI interface can be run independent of the HDMI. The software for dual screens is still under development. Running two screens at maximum resolution will depend on the speed of GPIO. This wasn’t possible on the Model A or B. And there’s a catch: as the board uses most of your GPIO pins, you lose access to them.