The Cisco Catalyst 9300 1100W Power Supply Unit, typically part number PWR-C1-1100WAC-P (or just PWR-C1-1100WAC), provides 1100 watts of power for Catalyst 9300 series switches, especially those with high UPOE (Universal Power over Ethernet) port requirements, supporting 115-240V AC input for enterprise deployments, often used in redundant configurations for high availability.