This is ULN2003 Driver Module Stepper Motor Driver, small size and easy to use. It uses the ULN2003 driver chip to amplify the control signal from the Arduino. This Ultra Lightweight and cheap option commonly used to run and control the small applications stepper motors.
Note: Color of PCB of may vary according to Manufacturer
HOW TO CONTROL STEPPER
The step motor is to a machine to convert pulse to angular displacement. So if you give stepper driver a certain pulse signal, it will drive step motor to a certain angle. you can control the angle the stepper moved by the number of the pulse. And you also can control the speed of the stepper rotate by the frequency of the pulse. The following picture is the schematic of the stepper driver.