Semperfli Micro Fritz

Kramer says:

This is a favorite material of mine as a synthetic substitution for pheasant tail. The material is small enough to tie down to a size 18 or 20, the color is always consistent, and it is far easier to tie with and lasts much longer on the river than real pheasant tail. It also comes in lots of fantastic colors, the tan and rootbeer being my two favorites for pheasant tail patterns. 

Semperfli says:

Micro Fritz is ideal for small fly bodies and micro thoraxes from lures to nymphs. With just the right amount of fritz for small flies sizes 16 to 20. As with all our Chenilles and Fritz materials these have cores that stop the fibres falling apart when tying your flies.