[chain777]

The thing that sets this apart from anything I've seen before, is the PCM has two tunes built in. Kind of like a motherboard that has a dual bios, and can boot to either one; one for day to day tasks, and one for max performance.

It makes sense to use a key, because the computer needs to be rebooted to change tunes. It gives you the same thing you would get if you used a flash tuner, but without the need to re-flash the PCM every time you want to change the tune.