The 5x5 USB Midi interface is based on the ploytec sources and comes with an preprogrammed chip (not soldered on the pcb)
the PCB is unpopulated
BOM and pictures:
https://diysynth.wiki.dsl-man.de/wiki/spaces/DSO/pages/1146929/USB+MIDI+Interface
Functions:
USB 2.0 - MIDI Interface - 5 Inputs, 5 outputs, LED status LEDS.
Please note: when the shop stock is on "Main" or "Haupt" it means, the stock is zero - it can happen when you try to order more than one pcb.