Featuring a rechargeable lithium-ion battery pack which provides up to 9 hours of game play, the R.A.T.9 comes complete with a unique desktop charging unit which not only charges your battery pack but also houses the 42 grams of removable weights which ship with the mouse. Two ‘hot swappable’ Battery Packs ship with the R.A.T.9, allowing gamers to use one pack while charging the other, negating the need to tether their mouse for charging, and always ensuring uninterrupted wireless play.