Hamilton 992

Here we have a Hamilton 992 model, 16 size, 21 jewels, in a very good 25 year open faced case.

This case features a "bull's eye" crystal. These has a flat, or concave, ares in the the middle. On this one that area is a little smaller than the inner area of the dial. Bull's eye dials were thought to be easier to read, although the theory behind this is rather specious.