The ER XENPAK module supports distances of up to 40 km on 1550 nm single-mode fiber (SMF). The XENPAK pluggable interface is an industry standard or Multisource Agreement (MSA) for pluggable 10 Gigabit Ethernet Optics. The ER XENPAK 10GBASE-ER transceivers are used by Ethernet service providers for inter-PoP connectivity.
Full specifications (PDF)
Manufacturer part number: 10112