The used Cisco C4KX-PWR-750AC-R 750W AC Power Supply is a power supply unit designed for the Cisco Catalyst 4500X switch. It provides 750W of AC power with front-to-back cooling airflow, ensuring efficient and reliable operation of the switch. This power supply unit has been previously used but has been tested and certified to be in good working condition, making it a cost-effective option for those looking to upgrade or replace their existing power supply unit. With its front-to-back cooling design, the Cisco C4KX-PWR-750AC-R power supply unit helps to maintain optimal operating temperatures and promote long-term reliability of the Catalyst 4500X switch.