ECM4000-28F-AC and ECM4000-28F-DC are modular, 'Hot Plug' power supplies that are used with the EC4660-28F Metro Access Layer 3 switch. They provide the flexibility of any misture of AC or DC dual redundant power sources for the switch. A second power module can be installed without interrupting the power supply provided by the primary module. The Modules are installed in PSU slots in the front panel of the EC4660-28F switch case, providing easy, field upgradeable access. With dual PSU's installed, an EC4660-28F switch is supported with full dual redundant power supply service. A modular Fan Tray is also available.