The FH-1 'faderHost' is a USB MIDI Host in an 8HP Eurorack module, allowing you to directly connect a USB MIDI controller to your modular synthesizer.
Using a suitable connector box (e.g. this) "USB MIDI controller" here includes an iPad or plain old computer.
As well as simple direct control of the output CVs from MIDI CCs, the FH-1 also offers
• LFOs on each output
• Step sequencers
• Polyphonic MIDI/CV conversion
• and much more
The FH-1 can be expanded with the FHX-1 Output Expander, for a maximum of 64 outputs.