The 100BaseFX SFP is a hot-swappable input/output device that plugs into a Fast Ethernet port or slot, linking the port with the network. It supports the in.pay-as-you-populate in. model and is interchangeable with other 100BaseX SFPs on the same line card. It supports the Cisco quality ID feature that enables the switch or router to identify whether or not the SFP is a Cisco qualified SFP.