2-Pack Blackout Roller Blinds for Windows - Light Blocking Shades for Bedroom, Living Room & Office

One of the other reviewers has described exactly how these work already and I'd second and recommend that review. What I love about these is the options they give you around hooking the blinds over the top of the window so you don't have to rely on the suckers but then they also provide the suckers just in case you can't use the hooks. I've put one of these in each of our two cars, a VW Polo and a VW Golf, unfortunately neither car was able to accept the hook over the top of the window so we're using the suckers in both cars. However, they're perfectly adequate and we've not had any incidents of the blinds falling off at any point. At the bottom of the blind is an option for securing it in place with a third sucker or with velcro (again all supplied). Another point worth noting (if you really are drawn to these by the hook over the window feature) is that I'd think for most cars with electric windows they're not going to accept the hooks - our Golf (with electric windows at the back) simply winds the window back down as it seems to detect a finger is trapped and so the safety mechanism cuts in to unwind again - our Polo (with manual windows at the back) was unable to wind the window up fully with the hook over the top. Don't get too caught up with these hooks though, the suckers really do work. For the price of these things I'd thoroughly recommend them!