The LC-MCCPWR-AC is a redundant power supply for the LC-MCC14AA chassis. It provides a simple and easy way to replace either of the Dual supplies that come with the L-com chassis. Simply switch off the supply, unscrew the bad unit from your chassis via the convenient thumbscrews on either side of the unit, slide it out and unclip the 5 pin header. Then install the replacement unit by reversing the process. Your chassis will continue to function normally, as these power supplies are hot swappable. These power supplies come with an audible alarm, and LED, that will alert you to any problems with the power flow or cooling fan.