Produced in Japan with strict quality control, Shimano Mastiff FC is 100% fluorocarbon line offering anglers consistency and reliability with strength, durability, and smoothness to enhance performance on the water. But Mastiff's benefits aren't limited to increased smoothness and suppleness, the most significant characteristic of Mastiff cannot be seen with the eye. Shimano engineers devised NANOARMOR® technology — nano-size ridges across the outer surface of the line — to enhance knot strength and toughness, preventing slippage and reducing the risk of line breakage. The added knot strength and durability are essential for enduring the repetitive stress when casting, twitching, or jerking large lures. Developed with one goal: Mastiff delivers connected confidence on the water.