SilverLine®-SF (Super Flex) SilverLine-SF is approximately 40% more flexible than traditional SilverLine. This is accomplished by replacing the steel center conductor with copper and the FEP outer jacket with polyurethane. SilverLine-SF retains its bent shape. That is, the cable has memory. SilverLine-LL (Low Loss) SilverLine-LL is a low loss version of traditional SilverLine.