Scientific Anglers Mastery MPXScientific Anglers Mastery MPX Fly Line The Scientific Anglers Mastery MPX is a versatile, smooth finish fly line built for the angler who wants one line that handles dry flies, nymphs, and small streamers with equal confidence. The MPX taper's slightly heavier head loads the rod easily at short range and turns over larger flies and heavier rigs without effort. AST slickness additive keeps the line shooting smoothly in all conditions. Technology: AST