Some fluorocarbon leaders are blended with nylon, lessening the benefits of abrasion resistance and low visibility. Pure fluorocarbon Mirage??? has the highest abrasion resistance of any leader or tippet. And its refractive index is so close to that of water that Mirage is virtually invisible. With a specific gravity of 1.76, it breaks surface tension quickly and sinks quicker than nylon, perfect for nymphing. Fluorocarbon materials retain their knot and tensile strength in water. Preferred for nymphing, especially in gin-clear waters or where fish are educated. Great for large streamers too. Outstanding turnover power, the result of patented extrusion taper technology, an Orvis exclusive. Fly fishing leader preferred in spring creeks, stillwater situations, for use with large streamers, or when fishing with nymphs in clear water where trout are fished over heavily.