One Way Vision (Perforated Foil) is an advertising application made on the glass surfaces of buildings. The most important feature of One Way Vision is that the inside is not visible when viewed from the outside, but when viewed from the inside, the outside is visible through the perforated black back surface. One thing you need to know when having OWV done is that normally only the advertising surface is visible during the day, but after dark, the lights are turned on inside and the outside is dark, so the person looking in from the outside can see inside.