This 8x8 LED matrix has a built-in MAX7219 chip. The MAX7219 is an integrated serial input / output common cathode display driver for driving LED matrix or 7-segment digital LED displays. This display module can work alone or in series to suit different applications.   

Features:

• Input voltage: 5V
• Size: 32x32x13mm
• Color: Blue
  

Pinout:

• VCC – 5V
• GND – Ground
• DIN – Data in
• DOUT – Data out
•  CS – Chip select
• CLK – Clock

Reference:

• Arduino Library