This shield (HCARDU0086) is designed to allow you to control a CNC router or milling machine from an Arduino board. It contains 4 driver sockets which allows compatible Pololu A4988 driver modules to be inserted (see HCMODU0068 on our website) providing the ability to drive 3 stepper motor axis (XY& Z) plus an optional 4th auxiliary motor. Additional connectors provide easy connection of end stop sensors and control buttons. (B.2)