Energizer 379 (SR521SW) Silver Oxide Battery (Pack of 5) Go to amazon.com Related posts Top 10 best battery 521: Which is the best one in 2022? FeatureWorld-class capacity and leakage resistanceUsed in watches, toys, glucose monitors, and calculatorsCell size: 379 DescriptionEnergizer 379 (SR521SW) Silver Oxide Battery (Pack of 5)