This is a fully assembled and ready to connect spindle speed control for the Brother C00 (and D00) controls. It consists of cable that connects directly into the SPOV socket on the back of the control, to a -50% to +100% control switch and a (non genuine) front panel knob.
Installation simply requires removing the screws from around the control screen (it's hinged, so quite simple). Then unplug the old blanking connector and replug in the new. Pass the switch through the faceplate and tighten into position. Fit the knob after aligning it correctly (so that it matches the range on the silkscreen labels)
Note that the front switch is deliberately non genuine so that it looks and feels completely different to the Feed Over-ride knob! I feel this is a big benefit for dealing with muscle memory which could otherwise be disasterous
Note also there will be long leadtime supplying these. The switches are quoted at 4-6 weeks from Japan for example, plus my time to assemble them before dispatch (extra day or so).