This view shows the top of the two previous LRIs [id=252599014] . On the left LRI at about the 1 o'clock position you can see the light arc, that is the inner edge of the smooth top. It is flat from the outer edge to that arc. Maybe only 1/8" or so, but enough to show the smooth surface-with faint carved lines from the mold itself. This is in theory how all of these Spratts should look on top. Very few seem to have this feature though. Info for the absolute specialist only I suppose.