I recently purchased the Korg VPT-1 from the Thomann Online Music Store, I think that it's a great product, it's exactly what I am looking for in fact, and I am quite satisfied with the overall features and performance of the VPT-1, in what it does to help my vocal pitch understanding and development, being a music enthusiast.
For instance it let's you see and comprehend more about where your personal vocal range is on the musical notation staves, so that you can keep your vocal pitch on track with practicing your music, with the help of the sharp and flat pitch indicators on the unit.
You can also switch between difficulty levels, Easy, Medium, and Hard, and if it's within your vocal range, you can move one octave up or down on the music staves.
The reference sound and sound back function are really good features also.
And in my opinion this item or product would definitely be a great help or asset to any D.I.Y. music enthusiast or professional musician alike. - Thanks to the good team at Thomann.