Teltonika PR4LC21K 1.25 Gb/s 20 km BiDi SFP Transceiver with Simplex LC

Fiber strands are often the scarcest resource in a link budget. Leased dark fiber is billed per strand, older outside-plant builds have few spares, and duplex optics burn two strands per link. The PR4LC21K addresses this directly: a BiDi SFP transceiver (module type IAE-SFP-G B20X-I) that transmits and receives over one single-mode strand through a simplex LC receptacle, delivering 1.25 Gb/s Gigabit Ethernet at distances up to 20 km. BiDi optics work by splitting the two directions of traffic onto different wavelengths over the same strand. That is why they deploy in matched pairs: the module at each end transmits on the wavelength its partner receives. Order the appropriate counterpart module for the far end of the link and verify the pairing before installation — two identical-wavelength BiDi modules will not link. The 20 km reach class puts real projects in range: connecting a remote well site, substation or gate house back to a main facility; joining buildings across a campus or industrial park; or tying a Teltonika-connected outstation into a municipal fiber ring. In the SFP cage of a compatible Teltonika router or switch, the module is hot-pluggable and swaps without host downtime. Alongside the short-reach multimode PR4DU22K and the copper RJ45 PR4JR20K, the PR4LC21K completes Teltonika's SFP lineup — this is the module you reach for when the run is long and the fiber count is one.