It this product were laminated, for durability, I would give it its 5 stars. After reading the above comments, I think everyone is a little lost as I was when I first purchased it, even after reading the reviews. When my son set it up on our standing piano, I finally figured it out; well, actually he did. He explained, "Oh, look mom, it's like a mirror!" I finally saw it too. It is to serve like a mirror image and help you figure out what the notes are, and where they fall in the black/white keyboard. Hopes this helps those were a little bewildered at the receipt. I wouldn't know how to place it on an electrical keyboard that has no backing like upright and baby grand, and grand pianos do.
I was a little dissapointed because it wasn't exactly what I was expecting. I bought it for my daughter...to have a wall chart or for reference when she is doing theory, and what I dislike is that if you have it facing you like the keyboard, everything is upside down.....and it is kind of large to have behind the keys.