Shimano's EX Fluoro Ocea Leader is a unique leader material designed for discerning anglers dealing with wary fish. The Ocea Leader is thinner then equivalent breaking strain nylon, highly abrasive resistance, doesn't absorb water which allows it to sink faster, is clear in colour and with its refractive index being pretty close to that of water, is therefore less visible to fish. Ocea leader also features a soft fluoro core for knot strength and a hard outer shell for abrasion resistance. A fluorine coating is then applied to the line to provide a smooth surface finish. Fluorocarbon Line remains clear underwater which makes it virtually invisible to any nearby fish. This is important when fishing in clear water, where line visibility has the potential to spook a fish from your bait or lure. It is also useful if the fishing is shut down and you want to try some finesse-style fishing.