Fastest1, Yes, that is the one. It sets on top of the machine and is for the Z axis that runs the quill up and down. When I got it unwrapped from shipment, the connector was loose and a pin had been broken off and stuck in the connector. I pulled back the wiring cover and discovered that only 4 of the pins are used so I straightened the pins out and re-connected the connector so now I will see if it will work. I wanted to see if someone had one just as a back up plan. What is the best computer to run this machine with. I have to find an older computer that will run the legacy type programs like Win98.