We like to call it the I/3/5 but whatever you call this line the fact is that it is one of the best sinking lines ever made. When you have to get deep this is the line you want.
From Scientific Anglers –
Get this: we took one of our most popular tapers, the Titan, drenched it in various mixtures of tungsten powder, and created a triple-density sinking fly line that will absolutely change the way you fish streamers forever. This is a fully tapered sinking line, so it casts like a floater but provides a straight-line sinking connection to your streamer. The days of chucking and ducking are finally over. Welcome to the triple-density revolution.
Loads quickly and delivers the biggest flies to the furthest targets. Excellent turnover due to short, powerful head and short front taper. Triple-density construction provides a straight-line connection to fly. Mastery Texturing reduces friction, providing longer casts, easier pick-up, and increased durability. For temperate climatesBraided multifilament core.
Sink Rates: Intermediate = 1.25 ips, Sink 3 = 2.5-3.5 ips, Sink 5 = 4.5- 6.0 ips