Ultra Power Alkaline Batteries w/ Duralock Power Preserve TechnologyPowercheck™ allows you to see remaining power at the press of a button. Ideal for medium-drain devices, Ultra Power provides more on-the-job power for your critical devices when you need it most. 10-Year freshness guarantee in storage. Duracell’s most powerful alkaline battery. Battery Type: Alkaline; Battery Size: AAAA; For Use With: High Power Digital Devices.