Sunlight reaching your car's glass arrives as visible light, ultraviolet and infrared. Infrared is the part you cannot see but can certainly feel, and it is a major contributor to how hot a cabin becomes on a still, sunny day. Kepler's IR and IR+ films are nano-ceramic, engineered to act on infrared heat as well as glare, which is why a lighter shade in the range can still be doing real work. That matters on a Tesla, where the glass area is large and the cabin takes on heat quickly. It also means shade and heat performance are separate things: compare the exact film and shade rather than assuming a darker film is automatically the cooler one, and ask your installer to talk you through the options for your model.