These are Dr Tom Whitings long dry fly saddles. These are ungraded so they tie from size 14-22. 10 Hackles per pack. Hackles are approx. 10" long so they tie a lot of flies from each pack. Spirit River continues to lead the way in UV2 technology. We have used a double dye process to give all our unique UV2 materials and flies the added UVF/UVR ultraviolet wave lengths. We all know UV Florescence which is so common on everything from street signs to bass lures. UV Reflectence is a spectrum of wave lengths humans can not perceive yet is extremely common in the animal and insect world. UVR allows mayflies to find mates, and bees to find flowers. Many male birds and bugs have a strong natural UVR signature.