The Korda IQ Fluorocarbon is a fluorocarbon leader material that has the same refractive index as water. This makes this line virtually invisible when in water. It is stiffer than normal nylon which significantly improves anti-tangle and anti-eject properties. The 10lb is ideal for a finely tuned rig in open water, 15lb is an excellent all-rounder and 25lb provides an impressive stiff-link. An exceptional high quality leader!