This cable connects an APC backUPS Pro or APC SmartUPS unit to a PC equipped with a 9 pin serial port. It is used to allow an APC UPS to communciate with a PC. Once this communication link is established, you can use either the APC Powerchute software or the power backup management software that may come with your computer to interact with the UPS and set up unattended shutdowns etc. 

This cable cannot be used with an Apple Mac. Please note that an APC UPS requires this specialized cable and a regular 9 pin serial or straight-thru cable will not work