Semperfli Fluoro Brite Fly Tying Thread - Fluoro Brite is a twisted fluorescent thread. To get it to lay perfectly flat simply untwist with your bobbin holder and then Fluoro Brite can be used as a flat floss. It has the most vibrant UV that fish find irresistible. Use it as a hotspot, for ribbing, a body or even a fab hot spot tail!. For tails, fold Fluoro Brite four times in a loop and tie it in the tail of a fly, cut to length then tease the fibers apart with a dubbing brush and you get an astounding crinkled tail with what looks like little firelights on the tail of your fly. Specially Formulated for Fluorescence Can Be Used As a Flat Floss Attract Trout, Salmon, and Other Species Fluorescent Materials Work Well One Hour Before Daylight and One Hour After Nightfall Recommended for Hooks 10 to 2/0 (But can be spilit smaller.) There 27.3 yards (approx) per spool of Fluoro Brite