Used to connect two serial devices together via their male 9 pin ports to enable communications between them. This female 9 pin d-sub (aka DB9) to female 9 pin d-sub cable features the crossed null modem wiring design, giving this cable its commonly used name. This type is also referred to as a 'direct' cable. Frequent uses of a null modem cable include networking two computers via their 9 pin serial ports or connecting a GPS device to a personal computer to upload or download information.