Specialized for use in intruder-style and other modern steelhead and salmon flies. The shanks have sought-after features such as a loop-up eye at the front of the shank, stronger stainless steel wire and a slightly smaller rear loop. 

To make the most of the possibilities a good reference is the book - Fusion Fly Tying: Steelhead, Salmon, and Trout Flies of the Synthetic Era - for 36 patterns that'll push your comfort zone and teach you to combine modern and traditional fly tying styles.