Cisco's GLC-SX-MM is a very commonly used SFP transceiver that works with 850nm multimode fiber and is designed for use in 1000Base-SX applications. They feature the small form factor duplex LC interface and are hot swappable for convenient, on-the-fly use in data closet applications.
GLC SX MM modules are commonly used for Gigabit Ethernet connections between switches, from switches to Wireless LAN Controllers, and between switches and firewalls. The convenience of the hot-swap modular design makes it a very simple and flexible for use in both simple and extremely complex networking environments.
Fiber Channel - Connecting servers to NAS or SAN devices. Many network and server admins find the constraints of typical server hard drive capacity too limiting. These admins opt to connect a server directly to a large storage device through a high speed fiber channel connection using the GLC SX MM module to provide extremely fast data transfer rates between the server and storage device.
Network devices that feature trunking capabilities can make use of multiple SFPs to provide extremely high capacity data trunks between devices.
The GLC SX MM modules I discuss on my web site are typically designed to work with the above applications types. The Cisco model is designated GLC-SX-MM and should be used for applications involving Cisco equipment for optimal performance.