The Cisco 100BASE-FX SFP Module is a hot-swappable input/output device that plugs into a Fast Ethernet port or slot, linking the port with the network. It operates on ordinary multimode fiber-optic (MMF) link spans up to 2 kilometers long. Supports the Cisco quality ID feature that enables the switch or router to identify whether or not the SFP is a Cisco qualified SFP.