The Cisco 10GBASE-LR Module supports a link length of 10 kilometers on standard single-mode fiber (SMF, G.652). Cisco X2 10GB LR is single mode 10GB transceiver works with 1310nm, its max working distance is 10km, the X2 10GB LR is compatible to IEEE 802.3ae for 10G Ethernet, it is plug in modules used on network equipment to connect to fiber optics.

The X2-10GB-LR is a highly integrated、Serial optical transponder module for high-speed, 10Gbit/s data transmission applications. 4×3.125Gbps Ethernet Signal Input by XAUI Interface.An integrated Coder / Decoder and multiplexer / demultiplexer (SERDES: Serializer / Deserializer). X2-10GB-LR is designed for 10km Transmission with a vertical cavity surface emitting laser (VCSEL). This X2 10gb transceiver Digital diagnostics functions are available via a 2-wire serial interface.

Ingellen is a leading manufacturer and supplier of fiber optic transceiver. They have a large quantity of Cisco X2 transceivers in stock and can ship the X2-10GB-LR transceivers to you within 24 hours. All of the X2-10GB-LR transceivers are tested in-house prior to shipping to insure that they will arrive in perfect physical and working condition. And they guarantee the X2-10GB-LR transceivers to work in your system and all of fiber optic products coming with a lifetime advance replacement warranty.

Specifications
Product Number: X2-10GB-LR
Product Name: Cisco 10GBase-LR 10KM X2
Form Factor: Plug-in module
Device Type: Transceiver module
Product Type: X2
Data Rate: 10Gbps
Wavelength: 1310nm
Datarange: 10km (6.2 miles)
Connector Type: SC Duplex
Cable Type: Single-Mode Fiber (SMF)

X2 10GB LR Features
Compatible with X2 MSA Rev2.0b
Support of IEEE 802.3ae 10GBASE-LR at 10.3125Gbps
Transmission Distance up to 10Km(SMF)
SC Receptacle 1310 DFB Laser
SC Duplex Optical Connector
Hot Pluggable 70-PIN Connector with XAUI Electrical Interface
Management and control via MDIO 2-wire interface
Power Supply :+3.3V, APS(+1.2V)
Diagnostic Optics Monitoring
Temperature Range: 0~ 70 °C
ROHS Compatible

X2 10GB LR Applications
10GE Ethernet switches and routers
10GE Core-routers
10GE Storage
Other 10Gbps Ethernet Transmission System

Please note:
Ingellen's Cisco module are not second hand but brand new compatible transceivers. Please feel free to visit the oficial site or directly contact Ingellen service( Service@ingellen.com)

source: http://fiber-optical-transceiver-module.com/cisco-10gbase-lr-x2-module-for-smf.html