There is no trick, just the laws of physics and optics. The human eye tends to notice brighter tones and colors about darker. So considering your sign from the surface the viewer won't see the holes - just the graphic image. I entered my VIN number for my 2012 Jeep https://mylestmfwo.blogsvirals.com/23503237/the-smart-trick-of-sticker-on-the-rear-window-that-no-one-is-discussing