This 7-Segment module has 8 displays, works on 3.3V and 5V and can be fully controlled with only 4 wires. This module is controlled by the MAX7219 chip. This chip is specialized in controlling 'common-cathode' displays with serial input as commands. This allows the displays to be individually adjusted, eliminating the need for the microprocessor to update all displays with a single change. In addition, this module has 4 holes in the corners for easy installation.