This expansion board as a driver expansion board can be used for laser engraving machines, 3D printers, CNC. 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. The CNC shield V3 for Engraving Machine 3D Printer A4988 DRV8825 driver expansion board is very convenient to use. After inserting Arduino CNC Shield V3.0 into Arduino UNO, and installed GRBL firmware then you can quickly DIY a CNC engraving machine. Features: Coolant enable Uses removable Pololu A4988 compatible stepper drivers. (A4988, DRV8825, and others) (Not Included) Jumpers to set the Micro-Stepping for the stepper drivers. (Some drivers like the DRV8825 can do up to 1/32 micro-stepping ) Compact design.