Review on 🖤 Opaque Matte Blackout Privacy Window Vinyl Film - VViViD Decorative Decal for Home, Office, Bathroom, Kitchen - DIY Easy Installation, Adhesive No Mess (17.75" x 60") by Nikita Sweet

That stuff! It blocks all visible light. I first tested it with my CREE tactical flashlight right in front of it and there was no sign of light. Note that this is "visible light". I actually bought this to try and hide the infrared LEDs on security cameras as the LEDs in close proximity produce too much light for my cameras and some of the infrared light still goes through this film. Although it definitely makes a big difference. Of course, ads don't block the entire spectrum of light, so I knew I was taking a risk. If you have trouble peeling off the clear backing, simply use a piece of tape (or similar material) to peel it off. I highly recommend this product. I'm constantly trying to find more ways to use this portable black hole.