Keego 100% Blackout PVC Light Blockers for Window Shades and Blinds - Block Light Along The Sides of Blackout Blinds Great for Bedroom Nursery, Light Blocking Strips (Silvery Grey, 58.5", 2pcs)

These work! Not too hard to cut, you just need a strong, metal cutting scissors. I took another customer's advise and used velcro strips to install these. Walls are NOT perfectly flat so the glue strip did not work for me. I bought velcro rolls available here on Amazon and they did the job perfectly. apply a long strip to the wall and stick the other part onto the L shaped side bar where the glue is (take the plastic off) It creates a perfect fit, firm and will block any light that could come in from the wall imperfections.UPDATE: I ordered two pairs of these light blockers. One of the pairs arrived DESTROYED. The second pair was fine but the box was also pretty beat up. Amazon ships these in a long box but it does not have any support or strengthening corners so when you receive them, the boxes are bent, torn and in some cases even ripped open. You can imagine how the contents arrive as well. I had to return one of the pairs TWICE because I received them BROKEN and bent on both the original order and the replacement order. NOT ACCEPTABLE!

Adhesive is very strong hopefully won't take the paint off if/when I remove. Bought for 2 windows and both came broken in the box, however I was able to make it work. Very hard to cut to fit.

It works as one would expect, and was moderately easy to cut if you're careful. But you should be warned that using scissors to cut it may result in it breaking since it is fairly rigid, I would recommend a hacksaw or rotary cutter. Contrary to what some of the photos suggest, it is NOT magnetically attached. It is just normal adhesive strips- I found this out the hard way when I tried to adjust it and I took off some paint. The adhesive strips are decently strong though, I can't see it falling off anytime soon.Another note- it is very rigid, so if your window frame is older and the surface you're adhering it to not perfectly flat then you may have some issues. I had to cut mine in 2 places to make it completely flush with the side of my windowframe, but that's due to a quirk in my building and nothing to do with the product.

I did the sides and bottom only and used black duct tape on the inside due to some light leakage. With these strips and the tape combined, it works great. In the picture, the before is on top and after is on the bottom.

They really help on the sides. Keep in mind light will poo from the bottom still. Also, if blind are not entirely rigid, light can vote up too.Thanks to Amazon and Vendor that sent a second pair when the first one got lost!