SFNB Basic Ethernet Switches Phoenix Contact's SFNB Basic Ethernet Switches feature a narrow housing design making them suitable for universal remote use in control cabinets and junction boxes. The SFNB switches have five or eight ports, up to two of which are glass fiber ports provided in SC or ST format. The Phoenix Contact FL Switch SFN Unmanaged Ethernet Switch provides increased network performance and easy network expansion, while the fiber optic options extend the distance and electrical noise immunity.