Florocarbon has the same light refraction qualities as water so it appears invisible to fish. It's more brittle than mono, and has zero stretch. But it also has a smaller diameter, so you can use bigger pound test than you would normally use in a mono. I used 14# test floro leader this last summer for those skittish steelhead . I believe it has the same diameter as 6# mono, but stronger. But I had about as much success just using 8# Ultragreen for steelhead when it was low and clear.