Ergonomic Mice

What is the battery life in the Microsoft ergonomic mouse 6000 th? It uses two AA batteries (Duracell or Energizer). How long will run the batteries.? Please help friends.thanks.this the mouse.http: / / images.google.co.in / imgres imgurl = http://www.geek.com/xyzimages/stories/reviewimages/microsoft_6000/nat6k_02.jpg&imgrefurl=http? : / / Www.geek.com/microsoft-natural-wireless-laser-mouse-6000 / & h = 301 & w = 401 & sz = 20 & hl = en & start = 4 & um = 1 & tbnid = qth76Qm8Onjj9M: & tbnh = 93 & tbnw = 124 & prev = / images% 3Fq% 3DWhat% 2% 2Bthe% 2Bbattery 2Blife%%%% 2Bin 2Bmicrosoft 2Bergonomic% 2Bmouse% 2B6000% 253f% 26um% 3D1% 26hl% 3This% 26sa% 3DN