Rio Deep 6 is a series of sinking lines that feature an increase in density at the front to ensure the line sinks tip first - aiding in bite detection and in setting the hook. These lines are made on a supple core for memory free performance and have a super smooth, tungsten impregnated coating that makes distance casting easy. These are essential lines for every serious lake fly fisher. Many years of testing by the world's most enlightened stillwater fly fishers has produced a series of lines with just the right sink rates to meet the challenges presented by many different kinds of lakes