S-35/53lc20d is a pair of sfp transceivers, the 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. The s-53lc20d is a 1. 25g single mode optical sfp transeiver with an lc connector, t1550nm/r1310nm, which works for connections up to 20km and supports ddm. . . Units are testedpatible with rb260gs, rb2011ls, rb2011ls-in, rb2011uas-in, rb2011uas-rm, rb2011uas-2hnd, rb2011uas-2hnd-in ccr1036-12g-4s. Unitspatible with non-mikrotik sfp devices as well. Product specifications details. Product code: s-3553lc20d. Data rate: 1. 25g. Distance: 20km. Mode: sm. Connector: lc. Format: sfp.