DB9 Male To Female Null Modem Mini Type

RS-232, DB 9 pin male to female null modem.

Null modems are used to connect two computers or other devices together to acheive file transfer.
Null modem connectors are different from straight through connectors because the receive and transmit conductors are crossed.
This is a miniature null modem with a male connector on one side and a female on the other.