20x duracell ultra power aa batteries and 20x duracell ultra power aaa batteries a third of alkaline batteries get thrown away with usable power still left inside them ultra power is the only battery with powercheck an in built tester that lets you know how much power is left so you get the maximum value out of your battery our most powerful alkaline battery ever using purer higher quality materials ultra power delivers up to 40 more power in high drain devices the cathode contains act