This soft, silicone-like cup, shaped like half an hourglass, is tied in behind the hook eye with the cup extending forward of the shank. Then a streamer pattern is dressed as usual, behind the head. The head can be used in two configurations. The cup can be pushed rear-ward over the head of the fly, where it functions like epoxy on a saltwater pattern to consolidate and protect wing and body materials at the tie-in point.

But the real magic here is when the cup is used folded forward over the hook eye. When the streamer is stripped through the water, the cup produces an astonishing, baitfish-like, side-to-side wiggle that is impossible to replicate with a standard streamer no matter what type of strip action or rod movement is used. The only other way to get this lifelike, lateral wriggling is with a diving lip, which besides being an utter nightmare to tie, twists the tippet unmercifully unless the fly is perfectly balanced. And it never is.

When I first saw this simple idea, I got two images in my head—striper flies—the smallest for trout patterns, the two larger for saltwater or big freshwater flies—in two cross sectional shapes, round and oval. But there are plans to add an extra-small version for trout an extra-large for bill-fish.

They come six to a package for $ 4.95 and are distributed by Hareline Dubbin and Raymond Rumpf.