These alkaline batteries have been engineered to deliver just the right level of power for most of your household needs. Plus, they’re fresh for 7 years. Many of the devices you use in your home are powered most efficiently by Duracell Coppertop batteries, including toys, remote controls, flashlights, calculators, clocks, smoke alarms, portable electronics, and more. The Duralock Power Preserve system is engineered to preserve power in storage. Batteries transform chemical energy into electricity to power your devices. If there’s a chemical reaction in storage, the active ingredients are oxidized, or wasted, decreasing your available power. By design, Duralock protects the power ingredients to help retain capacity.