Image shows Cisco 10GBASE X2 and Xenpak Modules

Product Overview
The Cisco® 10GBASE X2 modules (Figure 1) offer customers a wide variety of 10 Gigabit Ethernet connectivity options for data center, enterprise wiring closet, and service provider transport applications.

ain features of Cisco 10GBASE X2 modules include:
• Support 10GBASE Ethernet.
• Hot-swappable input/output device plugs into an Ethernet X2 port of a Cisco switch or router to link the port with the network.
• Provides flexibility of interface choice.
• Supports "pay-as-you-populate" model.
• Supports the Cisco quality identification (ID) feature that enables a Cisco switch or router to identify whether the module is certified and tested by Cisco.
• Has optical interoperability with respective 10GBASE Xenpak, 10GBASE XFP and 10GBASE SFP+ modules on the same link.
Cisco X2-10GB-CX4
The Cisco 10GBASE-CX4 Module supports link lengths of up to 15m on CX4 cable.
Cisco X2-10GB-LRM
The Cisco 10GBASE-LRM Module supports link lengths of 220m on standard Fiber Distributed Data Interface (FDDI) grade multimode fiber (MMF). To ensure that specifications are met over FDDI-grade, OM1 and OM2 fibers, the transmitter should be coupled through a mode conditioning patch cord. No mode conditioning patch cord is required for applications over OM3. For additional information on mode conditioning patch cord requirements please see: www.cisco.com/en/US/prod/collateral/modules/ps5455/product_bulletin_c25-530836.html.
The Cisco 10GBASE-LRM Module also supports link lengths of 300m on standard single-mode fiber (SMF, G.652)
Cisco X2-10GB-LX4
The Cisco 10GBASE-LX4 Module supports link lengths of 300m on standard FDDI grade MMF. To ensure that specifications are met, the transmitter output should be coupled through a mode conditioning patch cord. For additional information on mode conditioning patch cord requirements please see: www.cisco.com/en/US/prod/collateral/modules/ps5455/product_bulletin_c25-530836.html.
Cisco X2-10GB-SR
The Cisco 10GBASE-SR Module supports a link length of 26m on standard FDDI grade MMF. Using 2000 MHz*km MMF (OM3), up to 300m link lengths are possible.
Cisco X2-10GB-LR
The Cisco 10GBASE-LR Module supports a link length of 10 kilometers on standard single-mode fiber (SMF, G.652).
Cisco X2-10GB-ER
The Cisco 10GBASE-ER Module supports a link length of up to 40 kilometers on standard single-mode fiber (SMF, G.652).
Cisco X2-10GB-ZR: Supports link lengths of up to about 80 km on SMF. This interface is not part of the 10 Gigabit Ethernet standard but is built according to Cisco optical specifications.