Catalog > Internet of Things (IOT) Related Products > More Platforms GRBL Compatible-CNC Shield GRBL CNC Shield CMU CNC GRBL SHIELD GRBL COMPATIBLE-CNC SHIELD TO DRIVE 4x RAMPS A4988 STEPPER DRIVER BOARDS Discontinued Specifications, Prices & Availability may change without notice. Images are for illustration purposes only. E&OE Features This expansion board as a driver expansion board, can be used for engraving machines, 3D printers.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.UNO for ARD module IO port correspondence introduction.