PWR-C1-350WAC-P
350 W AC Platinum certified power supply module

Power Supply Modules Overview
The switch operates with either one or two active power supply modules. A switch that is part of a StackPower stack operates with power that is supplied by other stack switches.

You can use two AC modules or one module and blank cover. All power supply modules have internal fans. All switches ship with a blank cover in the second power supply slot.