RIO Glacial Gold Fly LineTHE ULTIMATE DEEP WINTER TROUT LINE with PolarFlex technology that keeps line soft, pliable, and functional in the coldest extremes of trout fishing temperatures. Snow on the banks? Ice in your guides? Cant feel your hands? Typical trout line coatings perform best between 40 and 70 degrees. Below that range, they get harder, stiffer, and more brittle. Memory becomes an issue and, even worse, ordinary fly line coatings are more likely to crack with