Adafruit 0.56" 4-Digit 7-Segment Display w/I2C Backpack - Blue

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. 

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.