When you buy an Automatic Tool Changer (ATC), the system might come with an orange switch box. That switch box is intended for use with the ATC on the D.Series line of CNC machines as well as the M.Series machines that DO NOT have a Tool Magazine on the back of the machine. If you did not purchase the optional Tool Magazine then you would need to use the Switch Box. If you have the Tool Magazine, then you DO NOT need to use the switch box.