The batteries being discussed here, as Buddy has said, are not rechargeable. They are significantly lighter in physical weight than their alkaline cousins. A 12 pack of these batteries weighs no more than 8 alkalines. They are good in heavy current applications such as in an HT dry cell pack, cameras, or in Buddy's KX1. I used them in the original Book Port, and in my Sony Mini Disc recorder, and observed a noticeable increase in useable battery time over standard alkalines. There is also a triple A version which I use in my Olympus DS50 when I know I will be recording with it for several hours. I should also point out that there is a slightly heavier, in terms of weight, lithium double A out there that is also not re-chargeable. I don't know what the difference is between the two models, but I think the lighter weight model actually lasts longer than the heavier one. The best price I have found for them is at Sam's Club. Mike Duke, K5XU American Council of Blind Radio Amateurs