Composed of 3 of the specialized Nickel Metal Hydride 5/4 AAA batteries, this battery pack is designed to replace a number of different battery packs from a vast assortment of brands including Sony, Radio Shack, Uniden and many more. Its NiMH composition allows the pack to hold a substantial charge, up to 800 mAh, and can deliver up to 3.6 Volts of power.