Evoluent is a tiny company with limited resources. We do not supply a Mac driver because the quantity of VerticalMouses sold to Mac users is very small, but the cost of developing a Mac driver is higher than for a Windows driver. The Windows driver has been in continuous development since 2002. It has gone through 3 developers and over 20 versions. Since we are not Mac users ourselves so we are unable to test the driver in day to day use, developing a Mac driver will be even more difficult. Therefore the Mac driver must wait until we achieve substantially greater volume.