Berkley's Trilene® 100% Fluorocarbon - Professional Grade™ is the ULTIMATE fluorocarbon fishing line PERIOD! Diameter for diameter it has the strongest impact strength of all fluororcarbon lines. It's the Ultimate in manageability and the ultimate in invisibility. With a similar refractive index as water, fish can't see it! It's easily the most sought after fishing line by most of the touring Pro's.