Danville 4-Strand Rayon Floss Fly Tying Thread - This 4-strand rayon floss material is 1200 Denier total strength. Each stand of the floss is 300 denier which makes this thread insanely strong. This floss lays down flat and can be easily split for use on smaller flies. This is a great a great material for Atlantic Salmon and traditional flies, and comes in some beautiful colors.