Avid Pro Tools MTRX 8 AES I/O, Plug-in Card, Suitable for Avid MTRX base unit (Art. #561742# - not included), Requires one module slot of the base unit, Expands an MTRX interface by eight input and output channels in AES/EBU format, Suitable, separately available breakout cable: Art. #580016#, Up to six cards can be installed in one MTRX base unit