content: I've been using one version or another of this Logitech, thumb-controlled trackball for about 5 years and I LOVE them. Takes about ten minutes to get used to, then you'll never want to use your old mouse again.Extremely comfortable to use. Never skips or lags. No picking up and repositioning because you've come to the edge of your mousepad.I'm just stunned that for as long as they've been out, anyone is still using those crappy old-style mice.