A little clarification, on this. You are correct and i must (NOT) throw some examples into certain named marbles which i have tendency to do so now and then. You are very correct in what you are say about the "Windshield" type. When i mention (family type) it means something similar to the name, maybe not being actually what it is. i am getting older now and sure DO NOT want to confuse this hobby any worse. If you took this example and reflect to the original "Windshield" only having green glass, what would it be then? The term "Windshield" is a and or a generalized term for a specific type. In Peltier you can find many that resembles these that have a lot oof open spaces to the look. Things like this makes for more discussion that helps the hobby. Your question is a good one, in reference to an Akro "Pop Eye", how much clear glass should it contain? Chuck G---