High quality dry fly by Fulling Mill from England.
The problem with most small flies is that it's really difficult to see them, especially in low light situations. That's the huge advantage of the Pinkie, tied by UK fly tyer Jeremy Lucas. Due to the pinkish CDC feather this small mayfly imitation is highly visible. And besides that, the pink wing seems to be an attractor for grayling as well.
Hook size: 17