Did a quick search for this on here but came up with nothing. Anyway... crowd-funded Midi interface, just saw a link on CSDB:
"This project is about a MIDI interface in the form of a cartridge to fit the C64 expansion port. It is for connecting MIDI devices such as keyboard and synthesizers, as well as file transfers from a PC or Mac. Additionally the cartridge provides an internal flash memory chip with a menu system, for saving your own programs and games loaded from the internet to the C64. The interface provides MIDI-in, MIDI-out and MIDI-thru. The MIDI-thru connector can be configured to mirror MIDI-in or MIDI-out. At one side is a reset button, which also launches the menu function."