I am writing this while sitting 1 foot away from a goldfinch eating at the window feeder on the other side of this mirrored window film, it works great to fool the birds. My only complaint is that it does not adhere to the window at all, it is just a roll of mirrored plastic sheeting. I had to tape it up, which means the optics are a little wavy, but I can live with that.

I bought these for my one year old nephew for Christmas. I figured he'd like to watch the birdies at the window while he was visiting. They didn't stay affixed on their own (which wasn't much of a letdown with all the condensation on the windows) so we had to tape them in place; otherwise they worked great! As long as he didn't make much noise he was able to get within a few inches of the window without scaring the birds away. It was a lot of fun to watch the little birder in the making (and they've held up well ever since).

This is our experience only. My wife and I were excited to find this product. We have the feeder on our bedroom window to enjoy the birds. The bird population is down but it has been bitterly cold and we had birds coming to the feeder. I put both pieces of the film up to cover the whole bottom of the window. In the first day we had some birds come to eat, and squirrels. Since then, the next four or five days we had no bird activity. I changed the feed and a couple of other things and still no results. The day I took the film down the birds returned to the feeder later that afternoon. Despite the cold weather, we have birds! It is really easy to put up and comes off just as easy. You also get the added feature of a sun shade for the room. The cold didn't affect it staying on the window. It is a good product as described. I just can't explain why the change in birds coming to the feeder with or without the film. For $9.99 try it, it's a non-mentionable loss if you have the same results we did. Enjoy God's blessing of birds and their songs!