This line suits the angler chasing redfish and wanting the rod to load fast with minimal false casting. Scientific Anglers gives the Amplitude Smooth Redfish Warm a short front taper for quick casts and a half-size heavy profile to help turn over larger flies. The AST Plus additive is there to keep the line slick.
All four sizes share a 31' head and a 100' total length. What changes is grain weight: 175gr in WF6F, 200gr in WF7F, 225gr in WF8F, and 260gr in WF9F (first 30'). The Warm version is intended for summer; Scientific Anglers lists a Cold version for winter.