They are designed to provide SDH SFP compliant links

The Eoptolink's Multi-rate Series 2.67Gb/s transceiver module integrates optics and electronics in a Small Form Factor Pluggable SDH SFP package. It is Multisource Agreement (MSA) compatible and designed for operation at 1310 nm and 1550 nm. Although optimized for OC-48/STM-16, it provides multi-rate capabilities and can be used from OC-3/STM-1(155 Mb/s) up to 2.7 Gb/s. MultiRate SFP transceiver provides a fully SONET compliant interface between the SDH SFP photonic layer and the electrical layer. Its microprocessor - based modular design implements all features specified in the SFP MSA compatible 2-wire Serial Digital Diagnostic Monitoring Interface for Optical Transceivers is a network line with transmission speeds of up to 2488.32 Mbit/s (payload: 2405.376 Mbit/s; overhead: 82.944 Mbit/s).OC-3/STM-1 is a network line with transmission speeds of up to 155.52 Mbit/s (payload: 148.608 Mbit/s; overhead: 6.912 Mbit/s, including path overhead) using fiber optics. Depending on the system OC-3 is also known as STS-3 (electrical level) and SDH SFP. These modules are also used for Fast Ethernet application.