The Bead Head Olive Prince Nymph Trout Flies in size 18 are a lot of 6 premium fly fishing flies designed for freshwater fishing. These flies are specifically targeted towards trout and rainbow trout, using various insect, midge, nymph, mayfly, and caddis pupa patterns to attract them. The flies are made from fly tying materials and are guide-tied for use in dry dropper or double nymph rigs. With a negative buoyancy and a maximum diving depth of 25 ft, these flies are ideal for tailwaters, freestones, and lakes. Made in the United States, these attractive green flies are a must-have for any fly fishing enthusiast.