Sunlight reaching your car arrives as visible light, ultraviolet and infrared. Infrared is the part you feel as heat, and it is invisible, which is why a film's appearance tells you so little about how it performs. Kepler's nano-ceramic IR and IR+ films work on that infrared energy along with glare and ultraviolet light, so the cabin gains less heat through the glass, the climate control has less to remove, and the interior gets protection from the ultraviolet exposure that fades trim and upholstery over time. Because the performance comes from the ceramic construction rather than from shade alone, a lighter Kepler shade is worth comparing on the published data against a darker conventional film. Ask your dealer for the figures on the exact film and shade you are considering, on the windows you plan to cover.