The black keys on this organ keyboard are notable. The temperament was before equal temperament when everything is a little "off" but equally "off" throughout the keys. Then, one can play in all keys. On this keyboard, the D# will be different from E flat, depending on whether you are playing in a sharp key or a flat key. The F sharp will not be the same as G flat, so there are two keys. I can't tell which is which from the photo.