While the outside is brightly lit i.e. daylight anyone looking in from the outside will see a mirror since the image of the bright surroundings, the outside, is reflected by the mirror. People inside do not see their own reflections, instead they see THROUGH the window film, and can watch the people outside. The opposite is said when the lighting conditions change i.e. night fall. People can start to see in while those inside see a reflection. There are ‘tricks and tips’ that acheive full 24 hour one way…place lighting outside and point it to the filmed glass. Outside lighting should be approximately 40% brighter than any lighting inside BUT you will have to test and increase the outside lighting to get the effect you require.