The Scientific Anglers Sonar Musky Sinking Fly Line is a fast-sinking musky taper used in moderate climates. This line features a powerful head to turn over extremely large flies. Scientific Anglers Sonar Musky Sinking Fly Line Features: Powerful head to turn over extremely large flies Reinforced loops Oversized running line for increased line management and positive strip sets Intermediate running line and Sink 5 head works well for lakes and rivers For use in moderate climates Braided multifilament core