I have two Nikon EN-4 and one Pearstone made in China. The end caps look like they can be interchanged. Do you know this for a fact? If you can't find a cap you could always buy one of the used batteries from KEH. They go as low as $7. Of course shipping will bring it up but it's one way of getting a cap. Old, used batteries aren't normally very good. I need another battery and am thinking about a new Nikon. But $99 is a lot to pay when a Pearstone is $29.