Article reference product: http://en.wikipedia.org/wiki/Eneloop (in English, dsl).
IMPORTANT: To take advantage of these batteries and maintain their performance longer, it is highly recommended to use a charger with intelligent 'charging the battery and not independently per couple. This type of charger, easy to find on Amazon for 30-60 euros, also will restore your old battery (feature 'refresh', count by 24 mini battery, normal length).