CopperTop Alkaline Batteries with Duralock Power Preserve Technology, D, 4/Pk, Sold as 1 Package, 4 Each per Package Get long-lasting, reliable power for the devices your business uses most. CopperTop? batteries are engineered to deliver just the right level of power for most electronic needs. CopperTop? batteries contain no added mercury and are rated for reliable operation in extremes from -4?F to 129?F. Individually date-coded and up to 10-year freshness guarantee in storage.