I made a couple of interesting discoveries at CES 2022, despite the in-person show being scaled back due to the pandemic. Once of those discoveries was Rolling Square, a Switzerland-based company striving to innovate for the tech minimalist. Their booth turned my head, intriguing me with their assortment of cabling options, power banks and other tech solutions. We got to check out the inCharge X, which Rolling Square charmingly dubs as the “100W Swiss Army Knife of Cables”. The inCharge X is the 2020 iteration of a product that started the ball rolling for Rolling Square back in 2014. It is a nifty keyring cable that is a USB-C, USB-A, Lightning, and micro-USB cable, all in one. It supports fast charging up to 100W and a data transfer rate of up to 480 Mbps / 60 MBps.
The inCharge X is easily one of the smallest and most practical accessories I did not know I wanted until now. If Rolling Square can do this much with such a small factor cable, I was surely curious to see what they can do in the realm of portable power. It was then when I also introduced to the Tau. The Tau is a miniature power bank that can be attached to your key chain while being armed with three connectivity options.
Tau Power Bank Specs
| Capacity: | 1400 mAh |
| Size: | 60x45x12 mm / 2.32×1.77×0.47 in |
| Weight: | 40 gr / 1.4 oz |
| Holdable Weight: | 350 gr / 12 oz |
| Connectivity: | Lightning, USB-C, micro-USB |
A purchase of the Tau power bank comes with a Tau charging dock, a USB-A to Micro USB power cable, screws, wall plugs, and a double-sided adhesive tape.
Build, Features, and Performance
The Tau is miniature power bank that is the size of a key fob. Making use of its size, the Tau features a key clip for adding it to your key ring. It has a battery capacity of 1400 mAh and houses three connectivity options: lightning, USB-C, and micro-USB. If you are wondering how three connectivity options are available from only two cables, the answer lies in Rolling Square’s dual connector. This dual connector is uniquely designed to fit in both micro-USB and lightning port slots while the Tau’s other cable houses the USB-C connector.
USB-C 
Lightning & micro-USB Dual Connector 
Lightning & micro-USB Dual Connector 
The Tau recharges its battery via its proprietary dock. The dock itself is space-conscious, being easily arrangeable atop of any surface or affixed to a wall. Setup is easy. Simply slide out the back cover, attach the included cable, and slide cover back into place. Rolling Square includes screws and wall plugs if you have a somewhat permanent spot planned for the dock. However, the included double-sided adhesive tape offers another mounting option for users that do not want to drill holes in their walls.
Right off the bat, the Tau is impressive with its super compact frame and highly portable design. This is as small as power banks get, sporting a size that is easy to slip into even the smallest of pockets. So, designing it as a key chain accessory was a very nice touch.
When docked, a powerful magnetic connector keeps the Tau in place as it charges. The magnetic connector is strong enough to hold both the Tau and the weight of a respectable number of keys. This allows you to hang the Tau with your keys on the wall of your choice, just as you might normally hang your keys by any door.
The included double-sided adhesive tape is also pretty handy in its own right. On one hand, depending on the surface, you can attach, remove, and replace the Tau’s dock as you see fit. Yet on the other hand, the tape is strong enough to hold the dock, the Tau, and your keys without slipping off the wall. To be honest, when I first saw Rolling Squares stock images and YouTube video showcasing this feature, I was a little skeptical. Yet, here is the Tau, in its dock, holding up a good number of keys and weight.
Now, let us dive into the meat and potatoes of any power bank, the charging. Even though the Tau sports both USB-C and lightning cables, it does not deal out the sort of “quick charging” that you could normally get with many rechargeable devices today. For example, a Qualcomm Quick Charge adapter and the InCharge X cable mentioned above can give you some impressive rapid-recharge rates. That said, the Tau still gets the job done in a reasonable amount of time.
Here, I took the Tau outside with me for some drinks and plugged it into my Samsung Galaxy S20, a phone with a 4000mAh battery. In under 40 minutes, I was able to get a little over 20% of battery charge from the Tau before it fully depleted. Getting back 20% of battery power into my device while was still powered on was not bad at all.
Tau Connected to the S20 via USB-C 
The Tau’s versatility with its three connection options further raises the power bank’s stock. It is truly ready to help with the emergency power needs of any mobile device out today.
Lightning Connection via Tau’s Dual Connector 
micro-USB Connection via Tau’s Dual Connector
The Tau’s dock took about an hour and 40 minutes to recharge the Tau from 0% to 100%. While the dock itself is very small, chances are that you will leave it at home. As such, a full recharge in less than two hours at home was perfectly fine for me.
Final Thoughts
From a power bank this small, around 20% of battery charge for your mobile device is a nice thing to have in a pinch. Not to mention, its three connectivity options make it hard to find a present-day mobile device that it cannot recharge. What I would love to see in a future iteration is the ability to recharge the Tau without having to depend on its proprietary dock. If Rolling Square can achieve that, even without implementing faster charging, then the Tau will be even more versatile than I could possibly imagine.
Considering the Tau’s exceptional portability and the fact that this power bank is only $29, I consider the Tau to be the perfect gift for either yourself or any techie on the go. If you are curious about checking out the Tau for yourself, you can do so by clicking here.
Also, if you are curious about the “100W Swiss Army Knife of Cables”, you can also check out the inCharge X by clicking here.
† As usual, there are no affiliate links contained within this post. We were provided a Rolling Square Tau power bank for review purposes and were not compensated for this review.