guys the batteries on amazon are not sold by amazon directly meaning it is not exactly always real. I have bought BL-5Js from amazon twice. first one looked very genuine. It even had the hologram, the only difference was that it said

"cell made in korea further processed in china"

whereas the one that came with the N900 just said

"made in china"

then the second time I ordered the exact same item from amazon (I now have 3 batteries) the hologram was not a hologram but just a 2D pic and the pin material looked slightly different and harder to get in. It's very difficult to know whether they are genuine but so far they all seem to work the same.