I took a first look at the battery pack this afternoon, and it has a significantly slimmer design than the old version. This version of the battery pack is thinner and longer, stretching as far across the back of the phone as it can before bumping into the camera bar. Slimming it down reduces the potential battery size, but it makes the pack more appropriately balanced with the phone as a result. The new model didn’t feel goofy to hold in the same way that the thick old version did.

Applying a battery pack to the super-slim iPhone Air comes with some drawbacks. Namely, it makes the phone bigger again. With the battery pack on, the iPhone Air feels a lot more like any other iPhone and makes it thicker than other iPhones, too. The battery pack is slightly thicker than the iPhone Air. In my brief time with it, the pack didn’t feel overwhelmingly bulky, but it tempered some of the benefits of the new phone’s design.

Another drawback: this battery pack is exclusive to the iPhone Air. While it can technically snap onto anything with magnets, it’s sized to fit the iPhone Air specifically. That means it might fit onto Apple iPhone Pro Max, but the smaller model — with a 6.3-inch screen compared to the Air’s 6.5-inch — likely won’t work.

Beyond that, the battery pack is styled much like the original. It’s light to hold and has a soft matte exterior. There’s a small light near the bottom that glows to show charging status when it attaches to a phone. I get the sense that many people will want Apple to bring this design to its other phone models. Or they’ll choose an Air so they can get this, regardless of whether the overall battery gains actually add up.