JUNSUNMAY DB9 9Pin Male to IDC 10Pin Female Ribbon Cable RS232 Serial Header Flat Cable, 28cm1. motherboards are extended with a 9 pin COM communication port. When you want to use the serial port for data communication, but you cannot find the DB9 serial port on the external interface of the motherboard, you can use this wire to lead out a standard DB9 pin serial port 2. Fasten a DB9 (RS232) Serial port to any computer system which has an RS232 serial panel mount receptacleFlat ribbon cable saves space and time in circuit interconnect