The black dots, or matrix patters, as well as the lines at the top of some windows are made of a Teflon type of material that is applied at the factory. Purely cosmetic, they hide trim lines and edges on different styles of autos. The thickness of these Teflon type areas make them a nightmare when applying window tint. Window tint is designed to adhere directly to the glass. The black lines across the top of some windows can prevent window tint from sticking and cannot be covered. When black dots are encountered, the window tint sticks to the slightly raised dot. This can give, depending on the thickness of the material, a lighter or different look in the area of the black matrix dots. This poses no risk of peeling. In some cases, the dot pattern or lines usually put at the top of some windows are so thick that it makes it impossible for the tint to stick at all.