Thank you, I saw the pictures that the trackball mouse and I wonder whether they are quite large in order to accommodate the trackball as I have a small palm(dwarfism).
The dimensions[1][2] when compared to standard mouse(e.g. M275)[3] seems to be about an inch higher(height, width), Also the GP comment says Ploopy was a bit large to use; Are the thumb trackball mouse inherently larger?