Actually this one the Low F# could be named 'Db' or 'Bb' or 'E', because the Diminished is not bound to a single chord like the other tuning layouts of our assortment. Somewhere along the way we decided to use to lowest note of the harp as the key, that is. The tuning suites very well for improvising over several chord structures and if you are familiar with Bending, you are able to play chromatically.