The CISCO A920-PWR400-A is a 400W AC power supply unit designed specifically for the Cisco ASR 920 Series Aggregation Services Routers. This model enhances the router's reliability by providing a redundant power source, ensuring uninterrupted operation in various network environments. Built to support high availability, the PSU can automatically switch to a backup power source if the primary AC power fails, minimizing downtime. The unit is hot-swappable, allowing for easy replacement or addition without powering down the network device, facilitating seamless maintenance and upgrades. Its high-efficiency design helps in reducing power consumption, contributing to a lower cost of operation and a smaller carbon footprint. The CISCO A920-PWR400-A is an essential component for network administrators aiming to bolster their network's resilience and operational efficiency.