The Rival Hera Thumbscrew is a great help for swapping batteries without tools, you'll understand how valuable it is when you're out of juice in a war without screwdriver at your disposal.
That said, it's not perfect, on my Hera, the screw is a tad longer than what the blaster can take, it cannot sit flush with the cover, but rather is protruding at an awkward 5mm above the cover. If you try to screw it in more, you'll get the feeling that one more mm will break the whole thing. Moreover, mine came with some scratches and dents, but I don't care about those
But still it's an invaluable tool, that would be perfect just if it was 5 or 6 mm shorter.
