The USB Overdrive is distributed as shareware. You can download it and install it on your Mac to see if it fits your needs. If it does, you can easily and safely buy it from the Kagi online web store. If it doesn't, the provided Uninstaller can remove the Overdrive from your system.

There are no feature limitations and no time limits in the unregistered version. The only annoyances are a gentle reminder at login and a short countdown when you open the user interface. I know that these things can be boring, but they allow me to keep working on the Overdrive.

But why should you pay for a device driver in the first place?

I'd love to give things away for free but writing software requires a lot of time and effort, not to mention the cost of all the USB devices I buy to make sure they work properly. I'll post a picture of my office someday, my friends call it the Mouseoleum. I also have two kids to feed, and their school and toys are definitely not free.

Note that USB Overdrive X licenses work with both Mac OS X and Mac OS 9 versions. Users of the Mac OS 9 version who registered after the release of Mac OS X are entitled to a free upgrade using the same code they already received. Users who registered before the release of Mac OS X can pay a discounted price for the upgrade to the Mac OS X version.