3M developed a patented technology for producing window film that incorporates a unique process not found in conventional films. Never before has anyone done this. In fact, it's so advanced that in time-based tests, 3M Scotchtint Color-Stable Auto Film held its color while most conventional dyed films rapidly changed to a purple color. High heat rejection without the interference of metals and a true low reflective factory-tinted look. No purple windows. Guaranteed! The 3M print mark is your assurance of authenticity. You know that your car features authentic 3M Scotchtint Color-Stable Auto Film when you see the 3M print mark on the window itself.