Parachute dry flies are very successful river trout flies.
This one is size 14 to imitate the Large Dark Olive (baetis rhodani).
It will work well in both fast or slow water and trout will readily take it when they are feeding on emergers, duns or spinners.
The yellow foam post makes it very easy to see even in faster broken water and in low light.
The Fly Fishing Punk 