3D Epoxy Eyes are absolutely sublime for fish imitations. Very nice finish and looks a million on the flies and are easy to use.

The number of eyes is variable, but there are always at least 20 eyes per package. Except for 10 and 12 mm, where there are 12 pieces per package.

3 mm fits the smallest flies.

4 mm is fine for smaller sandeels and gobies.

5 mm for slightly larger flies.

Here is a video for a flatwing tobis.