The StarTech.com SFP1000BXDST is an MSA compliant downstream fiber SFP transceiver which pairs with StarTech.com's SFP1000BXUST. They are designed, programmed and tested to work with 1000BASE-BX compatible MSA switches and routers. The SFP transceiver module supports a maximum distance of up to 10 km (6.2 mi) and delivers dependable 1 GbE connectivity over fiber cabling. We back all our cables with a lifetime warranty.