As Serial said, it doesn't need batteries only the
wireless version needs batteries. Don't buy the hype, take it from someone who knows! Its a waste of $50 if you already got a decent logitech or an intellimouse/explorer 3.0.
I think the DPI sensor "resolution" is a bunch of crap, I've used 5 different optical mice, 1st gen intelli explorer, then the logitech, then the 3.0, now the mx500. I've done stat tracking playing week on/week off with different mice and there was less then 2% difference in overall standings. These companies are full of hype and bs AFAIC, thats the only way to measure whether the mouse makes a noticible difference is stat tracking and graphing it over large enough sample of time. You can give a person the most aerodynamic super sensitive mouse in the world in the world but you still can't buy skill, awesome motor control, reflexes and fast response.
