...but that was just to get a left-handed one. The right button is the default primary one, but above all it's the physical form that's mirrored and fits better under the left hand (incl. thumb buttons on the right, not that I really use them).
Several manufacturers used to have leftie variants of mid-range mousies, but not anymore. :-(
Several manufacturers used to have leftie variants of mid-range mousies, but not anymore. :-(