S-35/53LC20D is a pair (S-35LC20D and S-53LC20D) of SFP transceiver S-35LC20D is a 1.25G Single Mode optical SFP module with a LC connector, T1310nm/R1550nm, which works for connections up to 20km and supports DDM S-53LC20D is a 1.25G Single Mode optical SFP transceiver with an LC connector,T1550nm/R1310nm, which works for connections up to 20km and supports DDM Tested and compatible with RB260GS, RB2011LS, RB2011LS-IN, RB2011UAS-IN, RB2011UAS-RM, RB2011UAS-2HnD, RB2011UAS-2HnD-IN CCR1036-12G-4S Connector: LC UPC; Data Rate: 1.25G; Distance: 20KM; Format: SFP; Mode: SM; Tested ambient temperature: -40 to +70C