This product is either discontinued or we cannot get that from suppliers.
Cisco C1-AIR-CT8540-K9 One - 8540 Wireless Lan Controller, Network management device, Rack-mountable - 2U, Processor 1 x Intel Xeon E5-2680v3 - 2.5 GHz, RAM GB 64, Hard Drive 240 GB x 2 - SATA 6Gb/s, Wireless clients 64000.
The Cisco C1-AIR-CT8540-K9 Wireless Controller provides centralized control, management, and troubleshooting for high-scale deployments in service provider and large campus deployments.