This is the English edition of a review from my Japanese YouTube channel, iestaLife. I review gadgets from my home studio in Japan, so product links go to Amazon Japan.
Quick take
Xiaomi’s UltraThin Magnetic Power Bank is a 5,000 mAh MagSafe-style battery that is about 6 mm thin and weighed 99.4 g on my scale — almost 20% lighter than the CIO SMARTCOBY SLIM 5K I normally carry. It looks great. The catch is the magnet: it holds, but it slides around far more than my CIO.
What I tested
- Xiaomi UltraThin Magnetic Power Bank (5,000 mAh), bought on Amazon Japan for ¥7,979 at the time of recording
- CIO SMARTCOBY SLIM 5K (5,000 mAh, Qi2), my everyday battery — with a MagSafe ring stuck on the back
- iPhone 17 Pro Max in a case with very strong magnets, and an iPhone 17 for size
What I found
- Weight: 99.4 g for the Xiaomi vs 121.3 g for the CIO (the CIO figure includes the ring I added, maybe 1–2 g).
- Rated output: up to 22.5 W wired and up to 15 W wireless, but wireless charging for iPhone is 7.5 W.
- The Xiaomi has a slightly larger footprint but is noticeably thinner. The USB-C port only just fits in its thickness.
- On the iPhone 17 Pro Max it charged fine and didn’t fall off when I shook the phone, but the bottom edge shifts easily. The CIO stays put.
- The back is smooth and silky, while the CIO has a grippy, rubber-like finish — that likely adds to the difference.
- It is almost exactly as wide as the standard iPhone 17. On a small phone such as an iPhone mini, it would stick out.
- The matte silver finish and the four-LED battery indicator look and feel premium.
Xiaomi vs CIO SLIM 5K
 |  | |
|---|---|---|
| Capacity | 5,000 mAh | 5,000 mAh |
| Weight (my scale) | 99.4 g | 121.3 g (with an added ring) |
| MagSafe hold | Weak, slides | Firm |
| Back finish | Smooth | Grippy |
Who it’s for
It suits you if you want the lightest, slimmest battery to top up your iPhone in a bag or pocket, especially with a standard-size iPhone. If you like using the phone with the battery attached — or, like me, stacking a phone ring on top of the battery and using it as a grip — get something with a stronger magnet.
Watch the review
The video is in Japanese. The shake test and the side-by-side with the CIO battery start at around 3:15; the weigh-in is at around 2:20.
Limitations
This was a first-impressions test on one unit, with my own cases. I didn’t measure charging speed, heat or how much charge it delivers; my guess in the video was “a bit over half” of an iPhone 17 Pro Max over wireless. The price is Amazon Japan’s at the time of recording.
Products
Xiaomi UltraThin Magnetic Power Bank (5,000 mAh): on Amazon Japan
CIO SMARTCOBY SLIM 5K (comparison): on Amazon Japan
The Amazon Japan links above are affiliate links. As an Amazon Associate, I earn from qualifying purchases. Check the listing for the exact model, current price and shipping availability in your region.
More reviews in English
All MagSafe Rings & Stands (49) →Browse all English reviews →
This review is also available in Japanese.