It is a double dye process to give all of their UV2 materials and flies added UVF/UVR ultraviolet wavelengths. UV Florescence is used on everything from street signs to fly tying materials. UV Reflectance on the other hand is a spectrum of wavelengths humans cannot visually see; yet it is extremely common in the animal and insect world. UVR allows mayflies to find mates, and bees to find flowers. Fish can see it, and they love it. UV materials and flies are becoming much more popular within the fly-fishing world because of the success they bring while on the water.