Created by Craig Matthews (the guy who came up with the Sparkle Dun and several other simple and effective patterns). These flies imitate a caddisfly that is stuck in it's shuck. These "injured and impaired" insects are easy prey for trout. That makes this pattern very effective. Although, it's general profile could also imitate a wide variety of bugs when viewed from underwater. I've had great success fishing these for our local trout here in VA and in WV.
These are sz. 16.