S-31DLC20D is a 1.25G SFP transceiver with a 1310nm Dual LC connector, for up to 20 kilometer Single Mode fiber connections, with DDM Units are tested and compatible with RB260GS,RB2011LS, RB2011LS-IN, RB2011UAS-IN, RB2011UAS-RM, RB2011UAS-2HnD, RB2011UAS-2HnD-IN, and CCR1036-12G-4S. Units are compatible with non-MikroTik SFP devices as well.