Review on 🌞 EcoNour Car Side Window Shade 20x12 (4 Pack) - Baby and Pet Friendly Sun Shade for Complete Infant Protection - Blocks 97% UV Rays & Heat - Rear Window Sun Blocker for Cars by Rich Schobinger

They might work for secondary car windows, but I used the first, one of two darker shades, on my office window to keep the sun out of the cars outside. That was my main goal in buying them. My neighbors often park their cars further down the street. Car windows are angled so perfectly that they reflect sunlight directly into my window for several hours in the middle of the day. Cars driving down the street towards my office during these hours also reflect the sunlight. The shadow on the window lets in just enough light that I can still see the basic shapes and colors of everything around me, while cutting the glare from the windshields so I don't burn my eyes when I head in that direction look to see what's going on outside. . The plastic backing adheres well to a clean window and its size does not obstruct viewing through the rest of the window.