The top of the screw of the light aqua CD 158.9 is concave and crude with no visual signs of rings or a triangle. Compare to the top of a blue aqua CD 158.9 [id=80236611]. Comparing descriptions of three other Screw-tops, it is obvious that there were four or more bottom mold plates. Could this mean that there were more than two mold styles or were the bottom mold plate changes made for a reason? Could it be the differences in production dates? Could the smooth tops be one year, the triangles another and then the triangle with the raised bead in the center another? We can speculate. Will we ever know?