The 4HR‐3UWX 4‐AA rechargeable battery pack utilizes SANYO’s new, Double X (XX) battery Powered by eneloop which provides 2500mAh of performance for long lasting, high power capacity, extreme applications. XX batteries are the perfect choice for powering high current consuming devices such as photo strobe flash lights; providing more than twice the number of flashes per recharge in less than half the time as compared to conventional alkaline batteries! Wireless keyboards, mice, game controllers, radio-controlled toys and a range of household devices can all realize extended performance when powered by XX batteries. Sanyo's engineers developed the XX batteries to excel in extreme conditions where high power performance in very low temperature environments (down to ‐4 degrees Fahrenheit) is needed. The new XX Nickel Metal Hydride batteries retain up to 75% of their capacity even after one year of storage. Unlike regular alkaline batteries which can only be used only once and are harmful to the environment, the XX batteries can be recharged up to 500 times. They come pre‐charged and can be used immediately out of the pack. XX Powered by eneloop batteries deliver reliable, high power battery performance when and where you need it most!