The Lenmar R2GAA4 AA Ready-2-Go Batteries hold their charge up to 4X longer than standard NiMH rechargeable batteries. Perfect for both low and high-drain devices. And they work with any NiMH charger. Lenmar R2G batteries are "Ready to Go" out of the package and have a shelf life of over 1 year. This means once you charge them up, they can sit in your drawer or device for a year and not lose their charge.