Ultra strong, supple, 100% fluorocarbon with high knot strength
Fluoroflex Plus is 100% fluorocarbon and the strongest, thinnest fluorocarbon on the market with incredible strength, for example: 5 lb for 5x material and is nearly invisible to fish. Fluoroflex Plus is incredibly supple and ties excellent knots even to nylon tippet.
Serious bonefishermen, nymph fishermen, and most hard-core subsurface fly fishermen won't use anything else but tough, durable, almost invisible fluorocarbon tippet. Fluoro is more abrasion resistant than nylon and almost impossible to see.