The effect is based on a so-called perforated film, which is a film with many small, evenly distributed holes. Your design is printed on the outside, making it clearly visible to viewers from the outside.
From the inside, however, you look out through the small openings. Since the human eye focuses on the brighter environment, the design "disappears" visually and the view to the outside remains unobstructed. This effect works especially well in daylight and is ideal for advertising applications on vehicles without significantly restricting the usability of the rear window.
