Sunlight reaching your Tesla's glass arrives as visible light, ultraviolet and infrared energy. Infrared is the part you feel as heat on your skin and the part that builds up in a closed cabin, and it is invisible, which is why darkness alone is a poor guide to how a film will perform. Kepler's nano-ceramic construction works across the solar spectrum rather than relying on pigment, so the film addresses heat and ultraviolet light while leaving the view through the glass clear. The practical result is a cabin that takes on less solar heat through the day, a climate system with less to fight against, and interior surfaces with less ultraviolet exposure over the years. Performance figures differ between the IR and IR+ ranges and between shades, so compare the exact film you are considering with your installer before deciding.