See Buying a used machine? - #5 by langmuir-aksel
They used to have a photo of the two enclosures in that post but its since been lost.
IIRC, the Pro only came with a Gen 2 controller.
EDIT: See CUT with Mach3 | Langmuir Systems
Second video in that sequence has a good photo of a Gen1 controller.
You need THC if you’re doing large cuts on thin material that will warp during a cut.