A fully assembled Macintosh to PC null modem cable. The Mac end of the cable is a 8-pin mini-DIN connector. The PC end of the cable is a female DB-9 connector. This cables primary purpose is getting old Macs online via a Raspberry Pi running SLiRP. Pinout: https://allpinouts.org/pinouts/cables/serial/macintosh-to-pc-null-modem.