The answer is HWIC- 4ESW module. It's an interchanging module on a router, to be exact it’s a high speed wan interface card with a few fast Ethernet interfaces. The 4-portCisco HWIC-4ESW EtherSwitch high speed WAN interface cards (HWICs) hardware feature is maintained on Cisco 1800 (modular), Cisco 3800, and Cisco 2800 series combined services devices.