... 1 km, are ideal for testing single-mode fiber spans (up to 50 km or longer) in Telco and Broadband networks. ... , connections, or other events. fiber boxes (FB) specificationsModelConfigurationFiber TypeFiber LengthFB1-SM-500-y1-y2Standard, one fiberSingle-mode, SMF-28 ... connectors for single-mode cables, specify type (e.g. ST, SC, FC)Other connector types, fiber types, and fiber lengths are available ...