I got carried away and forgot to tell you the keys. On the treble side the furthest row from the body of the accordion is set in B major scale, middle row C major scale and row closest to body C sharp (C#) major scale. What this means is you can play in all 12 chromatic keys. Each button is diatonic meaning pushing in and pulling out on the same button gives you a different note. With a bit of practice you can play the same song in all 12 keys which is something you cannot do on a standard diatonic. Each note can trigger a maximum of 4 reeds to ring at the same time. In the back of your treble keyboard, there should be some knobs which you can pull up or down allowing you to trigger or mute the reeds. This gives you 4 different sounds to play with (M, LM, MMM, LMMM). In addition to that, you have 80 bass stradella system like a piano accordion. Push and pull on the bellows gives you the same notes (There are many stradella bass tutorial videos on YouTube that covers this). This allows you to play chromatically on both sides of the accordion, but getting used to the mechanics takes a lot of discipline. If you decide to sell it, I’m sure you would have a lot of interest in Scotland and Ireland as BCC# Melodeons (Also known as British Chromatic) are big on folk scenes in these areas and Hohner Echo IV is a rare find. If you decide to learn/master it, I wish you good luck and keep at it, as the results is beyond rewarding.