Adafruit 0.56" 4-Digit 7-Segment Display w/I2C Backpack - BlueAdafruit
they have a built in clock so they multiplex the display. They use constant-current drivers for ultra-bright, consistent color, 1/16 step display dimming, all via a simple I2C interface. The backpacks come with address-selection jumpers so you can connect up to four mini 8x8's or eight 7-segments (or a combination, such as four mini 8x8's and four 7-segments, etc) on a single I2C bus.
The product kit comes with:
- A fully tested and assembled LED backpack (uses I2C 7-bit addresses between 0x70-0x77, selectable with jumpers)
- Ultra-bright 4-digit 0.56" tall white seven-segment display (Blue)
- 4-pin header
Note: A bit of soldering is required to attach the matrix onto the backpack but its very easy to do and only takes about 5 minutes.