When we are doing robot experiments, it needs to use multiple PWM ports to drive the servo motor, however, the common used Arduino UNO R3 only has 6 PWM ports, so it is not enough.
This allows you to use this expansion board, which is directly stacked on the Arduino UNO R3 board and can drive up to 16 servos. It uses I2C input, just occupies A4 and A5 of the Arduino UNO R3 board. The expansion board contains PCB double sided holes ,which can direct to solder with components to build up prototyping circuits.