Also there are provides Cisco SFP 1.25G other Compatibale brands

The transceiver operates from a single +3.3V power supply over an operating temperature range of 0 to +70C. The transmit and receive functions are contained in a SFP 20 pin package with a Duplex LC or SC connector interface. The transimpedance amplifier IC has internal AGC for wide dynamic range. The postamplifier is AC coupled to preamplifier through a capacitor and a low pass filter. It can be enough to pass the signal from 100Mb/s to Cisco SFP 1.25G without significant sensitivity. A Signal Detect status output flag is also provided.SFP Transceiver Modules - hot-pluggable module, the greatest rate up to 10G, multi-use LC interfaces. SFP(small form pluggable) can be understood since the upgrade version of GBIC. SFP module volume ratio reduced by half than GBIC module, the identical panel could be configured in additional than double of ports. Other functions of SFP Module are do i think the GBIC basicly . Items like Cisco SFP Modules(cisco mini gbic) tend to be smaller and so are just about half the dimensions of GBIC optics. These modules send speeds that range between 100Mbps to about 4+Gbps. Their transmission length begins at approximately 500 meters and goes up to 120+ kilometers.Divided by rate :155M/622M/1.25G/2.125G/4.25G/8G/10G,155M and Cisco SFP 1.25G market is used more, 10G technologies are maturing, demand is always to increase quickly.