Use a curved hook, add some weight, some Riverruns dubbing and a rib and you are ready to tie a   perfect Gammarus (or shrimp) imitation in no time-a true killer for both freshwater and saltwater fly     fishing. 

BTI-09D-5003 Gammarus Back

6 best selected nature colors: Green, Olive, Orange, Pink, Salmon and Tan.

3 popular sizes, S 0.6inch/1.5cm (hook size 12-14), M 0.64inch/1.7cm (hook size 10-12), L 0.8inch/2cm (hook size 8-10). One sheet one color, 14pc S, 14pc M, 12pc L, total of 40pc per color. 

They also make great amphipod and euphausiids for Sea-run Cutthroat Trout in the salt water. They are pre-cut, pre-formed, flexible, waterproof, and UV resistant. Proudly from Europe.

Gammarus nymphs are deadly for trout & grayling and indeed for coastal fishing for sea trout or sea run browns, so a Gammarus pattern is a "must-have-in-the-box"pattern when fishing. 

Unit price is USD1.8-2 for each color jungle cock substitute