There's a good reason for that, though: you can take it apart without tools, swap out weak cells for fresh ones when the time comes, and keep using it for way longer than any other power bank will last.

Ctrl Energy, the Paris, France-based firm behind this, says its idea was to create a device that wouldn't become obsolete or need to be entirely trashed just because it wasn't operating at its best. That's why the Zero isn't sealed, and why it uses rechargeable batteries that you can buy anywhere.

The power bank's lid is magnetically attached, so you can remove it at a moment's notice and chuck in new cells when the old ones don't hold their charge as before.

The Zero holds six 18650 lithium-ion cells of 3,500 mAh each, which works out to about 21,000 mAh. Its USB-C port lets you charge other gadgets at up to 100 W, and you can top off the Zero itself at the same rate. An additional USB-A port does 18-W charging, and you can also wirelessly charge devices at up to 15 W.

The company recommends replacing these with validated cells from Samsung, LG, or Molicel. These can be had from most ecommerce stores like Amazon for just a few dollars each. Alternatively, you can order a refill of cells from Ctrl Energy itself.

Now here's where things get interesting. This isn't just for charging devices using a cable. A magnetic interface on the side lets you connect add-ons and customize your Zero.

That includes a flashlight, additional USB ports, a snap-on panel light for enhancing video recording, and a face-tracking tripod that can hold the Zero and your magnetically attached phone.

Using additional Zeros and an add-on that synchronizes multiple power banks, you can create it a power station that can top off many more devices. Up to five Zeros can be chained together into a 105,000-mAh colossus for extended outdoor adventures.

You can even connect a foldable 18-W solar panel and top off the Zero when you're off the grid.

The Zero also hides a couple of clever tricks in its design. That prominent cutout near the top acts as a handle and a way to hang it from your gear using a carabiner. It also makes room for the camera module of an iPhone when you stick the handset on to charge wirelessly. Lastly, it can hold a cable winder that you can 3D print yourself.

Now, if this is too big, you can also get the Subzero, which uses a replaceable 5,000-mAh cell and works with magnetic add-ons just like its sibling.