I was going to mention this before but did not think anyone had every heard of it,, Well, My car was double tinted with 35% all around, Somehow this provides better protection in the hot houston sun, I have my windshield also tinted only one time with 35%. I believe that my double tint looks better than a single 20% tint,,deeper charcoal look to it, and it does keep the inside of my car nice and cool.