This is an A+ Certified Pre-Owned Cisco WIC-1DSU-56K4. This Cisco network interface card, WIC-1DSU-56K4 will provide the most reliable network connections and expand network capabilities of your Cisco router. The 4-wire 56k CSU/DSU implements switched 56k and DDS (leased line) operation. The hardware feature set is identical to the 4-wire 56/64k CSU/DSU for the Cisco 2524 and Cisco 2525; the Cisco IOS configuration is also the same. Enjoy great savings and unmatched value when you buy WIC-1DSU-56K4 from UsedCisco.com.