The Jiggy is a popular saltwater fly for striped bass fishing. It is the fly you want when sand eels are present.
The Jiggy is a weighted fly with some similarity to the Clouser Deep Minnow. However, it uses a metal cone head for weighting instead of dumbbell eyes. The cone head weighting has the advantage of being somewhat more durable when used as a sand eel imitation that is fished in a manner that bumps it along the bottom.
The Jiggy Fly is tied such that the hook shank is along the bottom with the bucktail angled up and covering the point of the hook. This gives the fly some resistance to snagging along the bottom. The Jiggy can be tied with synthetic materials such as ultra hair or super hair as well as with bucktail.
More information about Bob Popovic's flies can be found in his book
"Pop Fleyes: Bob Popovic's Approach to Saltwater Fly Design", which he co-authored with Ed Javorowski.
If you are going to fly fish for striped bass, make sure you have some Jiggy Flies.