The pictures above are of the 3m Crystalline window film. This window film is the only DOT legal window film available for your windshield. DOT law says that you can not put anything on your front windshield that causes an obstructed view or darkens the window more than 70% total light transmittance. Most windshields are around 80% VLT. Combined that with anything darker than 90 and you won't be legal. This film doesn't change the look of the windshield at all. You won't be able to tell there is anything there by looking at it. It has a 1700+ spf and blocks 97.5% of inferred light. Inferred light is responsible for the heat you feel. This film is constructed using over 220 layers and is the most advanced window film technology in the world. Crystalline window film also blocks 99.9% of UV light and has higher heat rejection than most of today's darker film's. Most window film's are not designed to block inferred light, although some inferred is blocked with conventional window film's, it is very low.
Some companies are selling Llumar Air Blue 80 as a dot legal film for your windshield. It comes in 80% and would be legal if your windshield didn't have any tint from the factory; but it does. All cars and trucks have a very light tint to the glass from the factory. Air Blue 80 will make your windshield around 64% and will not be DOT legal.
Also available in darker versions for the sides and back windows for those that like the darker look. Crystalline window film comes in 90, 70, 60, 50 and 40% Visible light transmittance.
Read more on tinting your front windshield.