The Cisco C3KX-NM-10G is a network uplink module for Cisco Catalyst 3750-X and 3560-X switches (note: "3506X" is a common typo for 3560-X). It features four physical port slots: two slots support 1-Gigabit SFP, and two slots support both 1-Gigabit SFP and 10-Gigabit SFP+ modules.