If you prefer our traditional teardowns, check out our step-by-step teardown of the Apple Watch Series 5.

The big new feature on the Apple Watch Series 5 is its always-on display. Now you can tell the time, anytime—an “innovative” feature that my $20 Timex has had for ages, but it’s easier said than done on a complex device like the Apple Watch. That’s why what really matters is on the inside. Here’s what our teardown uncovered.

UPDATE (9/25/19): We got around to opening up the 40 mm model and noticed a significantly different battery. This one has a snazzy new metal casing, as well as 10% more battery capacity than the Series 4 40 mm model. Read more about our discovery here.

From the outside, it’s hard to distinguish the Series 5 from the Series 4, unless you flip that bad boy over to see the “Series 5” printed on the bottom. The opening procedure also remains the same—some heat to soften the adhesive and a precision knife to separate the display.

Series 5 on the left, Series 4 on the right.

On the back of the display assembly, we hoped to get a closer look at what makes the always-on display tick. Apple stated that the Series 5 uses advanced display drivers, an improved power management chip, and an improved ambient light sensor compared to last year’s Series 4. But the real improvements are baked into the display tech invisible to the human eye, as detailed in our in-depth blog post on LTPO technology.

The back of the Apple Watch Series 5 display and the accompaying X-ray, courtesy of Creative Electron.

The improved, if not altogether new, ambient light sensor is visible in our X-rays, embedded under the OLED panel. But the built-in compass is new, and supposedly uses a very tiny gyroscope (and presumably some very fast math) to compensate for interference from the magnets inside the watch.

The battery is a hair bigger (1.4% in the 44 mm model) than in the Series 4—which isn’t much, so the always-on display probably owes its existence mainly to the aforementioned efficiency improvements. As for removing the battery, you know the drill: it can only be disconnected while in the process of prying it out of the case.

Series 5 battery on the left, Series 4 on the right.

The Series 5 uses Apple’s new S5 system-on-chip, which packs in twice the storage and the new compass. But it also contains the same CPU and GPU as the S4 chip in the Series 4, and the overall performance specs are the same.

Other than that, the Series 5 is very similar to the Series 4 on the inside. But Apple has made enough minor changes that many parts are not interchangeable, thanks to redesigned connectors on the taptic engine, display and battery.

Now, about Apple’s claim that the Series 5 Sport cases are made from “100% recycled aluminum.” While using recycled materials is great, the truth is most of the world’s aluminum is already recycled, and recycled aluminum is dramatically cheaper than the freshly-mined variety. The real question is whether Apple uses any recycled aluminum that wouldn’t have been recycled anyway. And after analyzing Apple’s statements on the matter, the answer seems to be no. Apple is in line with industry standards, and isn’t remaking the field. Recycling all the lithium or cobalt in their batteries would be a true leap forward, and Apple may well be working on something like that, but using recycled aluminum isn’t much to get excited about.

In any case (no pun intended), the Apple Watch Series 5 earns a repairability score of 6 out of 10 (with 10 being the easiest to repair).