Four Digit (5 x 7 + 1dp) LED Matrices for use with the Adafruit 16x9 Charlieplexed PWM LED Matrix Driver - IS31FL3731 (Adafruit Product ID: 2946). Up to four units can be used on the same I2C bus (addresses 0x74, 0x75, 0x76, and 0x77).
Arduino library.