Super strong nylon.
RIO® Powerflex is a very complex nylon co-polymer that has twice the strength of single strand monofilament for its diameter.
This material is useful for all fly fishing, but especially for freshwater fishing. It's suppleness makes for great drag free presentations of both dries and nymphs.The light gray color provides super camouflage in any subaquatic environment
Powerflex has become the industry standard for high tensile strength, good knot and shock strength, and accurate diameters.