just avoid a4tech brand, ang dali masira last year tatlong mouse ang bumigay.. i tried their optical mouse..it was fine..when it worked!..ayun nagweird may utak ng sarili.. hay i gave up on that brand (maski yung normal nilang mouse madali din masira, sa office sira din kaagad).. now im just using a normal Genius mouse.. alang problema...konting linis linis lang ng roller ehehe