This two part tim is slightly confusing: the first part is an essentially flat rim lip and the second part rounds down to the neck. It's not really indented and it's not really 'rounded.' The rim itself is rather inconsistent, so an exact diameter estimate was difficult.While the color of the exterior surface is black, the vast majority of that surface is covered with a pale brown layer of corrosion. The interior surface is much less corroded. Designated MAE 653.
From Interior to Exterior