I have been using Danville 210 Dernier Flymaster Plus as a substitute for the 3/0 monocord. It is a bit thicker than the 3/0 monocord and stronger. I still have a dozen spools of monocord but only two white which I use extensively for warmwater and saltwater streamer patterns. I am reserving those for flies sizes 6 or smaller and using the Flymaster Plus 210 on stuff up to size 1 or 1/0. I use Danville Flat Waxed Nylon on the larger stuff.