Look at these two lamps; both are Centuries; but one is older than the other. The one on the left was given to me by a former customer of mine from Walgreens. The one on the right is a newer one I have always had. I noticed the left one has no heat ring? Any accounting for this? Also it has more light holes on the side or they are spaced differently. I tried to put a heat ring in it; and it just sinks through the middle; to the bottom. Did the Century model ever another bulb other than the 40W A15 Appliance?