HiLetgo&reg; 2pcs V3 Engraver Shield 3D Printer CNC Expansion Board A4988 Driver Board for Arduino Each road stepper motors only need two IO ports This expansion board as a driver expansion board, can be used for engraving machines, 3D printers. PWM Spindle and direction pins. 4-Axis support. Runs on 12-36V DC It is a total of four slots, can drive four A4988 stepper motor. Each road stepper motors only need two IO ports. In other words, six IO ports can be well managed three stepper motors. Very convenient to use. Stepper motor wiring as follows: 2A, 2B is a group (red, green), 1A, 1B is a group (blue, yellow), if want to change direction, can be change the position of one group , for example 2A, 2B mutually exchanged.