These are sold through DekCell, whose website seems gone, but Amazon did deliver their battery for $19.99USD w/ free ship.
It's definitely a knock-off--fine w/ me since I want fresh cells.
It's also not "extended." It's the standard size, 2000mAh. Mine arrived, it works, the price was right: that's the extent of my vouching, but I haven't found anything better/cheaper.
It's also "cojon-free," for those, like me, who never had the cojones to tear down a J battery and replace the cells
Jake