Scientific Anglers Sonar Seamless Stillwater Sinking Line - Sink I/Sink 3A unique departure from graduated density lines of years past incorporating a smooth, seamless transition between multiple density sinking rate sections and eliminating the hinged effect that plagued previous multi density lines. Sonar Stillwater Sinking lines provide straight line connections to subsurface flies, keeping you in control of the fly every second its in the water and adding the ability to feel and set the hook earlier. Code Line Head