T337G: Inner Side Windows
 

I own a 1974 T337G. I am in the process of upgrading my interior and want to replace the inner side windows with new clear plastic. Of the total of 8 windows, 6 are .080 thick. The second and third windows ( numbered from the front ) on the right side are .187 thick.
Does anybody know why these two inner windows are thicker? Is anyone aware of a reason why I cannot use .080?
Thanks,.....

Is not your aircraft pressurized?

Yes, my aircraft is pressurized.
I am not disturbing the outside pressure containment windows.
The windows I am referring to are the inner windows. These windows do not serve to contain pressure. They appear to be more decorative in nature.

Protective.

They protect the pressure vessel windows from silly passengers and sharp objects.

Thermal insulation too!
 

I also think the double windows are for thermal insulation.
For high altitude pressurized and turbo aircraft, even in summer, 'baby it's cold outside'