3.5 mm. Single ocellus (photo 3, taken through microscope).
I found this woodlouse under a rock at a dock. I lifted it and put it on a piece of wood, in order to take the picture. It moved slowly away from the piece of wood to get under a rock again. It was around 1/3 inch long, with brown and black colors. It had feelers and several pairs of short legs.
I finally found another one! I didn’t actually realize this was a Miktoniscus when I found it. I’m going to have to collect some specimens to examine under a microscope to figure out which species they are.