I've struggled with the modes, like a lot of guitarts have off and on for some time and this wheel pretty much solves my headache!! All you do is set it to the key you want to play in and read the notes and chords off. Can't believe anyone hasn't thought of doing it this way before now. It might be useful for guitar teachers?. There's some chord reference charts on the back which I didn't need, but I can see how they might be useful to some people. The solo guide is pretty useful too. Great product!