eneloop pro AA and AAA NiMH ready to use rechargeable batteries utilize Panasonic advanced rechargeable battery technology allowing them to be recharged up to 500 times. eneloop AA and AAA rechargeable batteries deliver consistent extreme power performance maintain 85% of their charge for up to 1 year (when not in use) come pre-charged by solar power (at the factory) and are ready to use out of the package. These eneloop batteries also feature extreme temperature performance down to -4 degrees Fahrenheit. Pair eneloop and eneloop pro AA and AAA batteries with Panasonic advanced quick advanced or super quick advance eneloop or eneloop pro chargers to maximize your rechargeable battery experience.