This is the 'low end' version of the series. I have to admit, it takes some getting used to at first, it's definitely not the average mouse.
However, if its ONE thnig and one thing alone. The thumb rest is a revelation. to quote another reviewere, I never knew how much my thumb lagged until i used this mouse. The mouse buttons are large, crips and well the DPI goes up to 4000. its fully customizable i.e. all the buttons can be programmed providing u install the software.
I've been having great fun fiddling with the extendable back, making the mouse perfect forany size hand. the thumb wheel, while a little akward can be programmed to do any number of things. i'm going to try and set it to pc volume. lol