Arduino processor – the electronic brain. The Nano processor is plugged into a shield (hey that’s what they call it). The shield allows a myriad of imaginative things to be plugged into the processor. This allows one to easily expand the Teralign mechanism. If for any reason you need a replacement, we offer it here. It comes with its own separate USB cable allowing you to change the Nano’s programming. Don’t worry, we are also making available the programing code for free!