The FFC connector on the Robin module is used for the GPIOs, one [Article not found #100606] Slot and the USB Client detect.
The flat flex cable (FFC) can be ordered from Molex:
Please note, that Daisy V1.0 has the FFC connector slightly shifted in regards to Robin. This may lead to problems using a very short cable.
Daisy V1.1 solved this issue.