We live in the age of battery anxiety. Will our phone last the day? Will our earbuds need recharging mid-commute? Rolling Square, the company behind the brilliant AirCard, has a new, pocketable battery that fits on a keyring and offers peace of mind if your gadget runs dry when you need it.
And it does a lot more, with features including a Lost Mode, using the company’s bespoke Sherr.it platform, which works as a locator, just like the Apple AirTag, through a QR code on a sticker supplied in the box. But the Tau 2 does stuff the AirTag can’t. Here’s all you need to know.
The Pocket-Sized Power Bank
The Tau 2 is a chunky little device, but light and pocketable. There’s a ring on the top so you can attach your keys to it. Pull it off the keyring to reveal two short connectors. One is USB-C, the other, cleverly, is a dual connector with Lightning and Micro USB. Slot the correct one into your headphones, phone, camera, Bluetooth speaker or whatever, and tap the logo twice. It’ll then boost the energy of your tired gadget.
Tiny though it is, it has 2,000mAh capacity, which is enough to add around 26% to the battery of the iPhone 15 Pro Max, 34% to the iPhone 15 Pro, 22% to the Samsung S24 Ultra and so on. Nowhere near a full charge, but more than enough for emergencies, which is its main purpose.
Charge On The Keyring
This is neat. Once you’ve put it on your keyring, you probably want it to stay there, right? Relax, you don’t need to remove it from the keyring to recharge it.
The supplied charger can be mounted on the wall or desk via an adhesive pad and links magnetically to one end of the Tau 2.
So, if you place the charger on the wall near the door, or on your desk, wherever you usually keep your keys, in other words, it’ll be charged and ready to go when you grab your keys and leave.
To get to the charging cables inside, you just pull on the Tau 2’s case next to the keyring end. In fact, attaching keys makes it easier to detach the cover.
There’s another neat feature: you can charge the Tau 2 from USB-C as well—just tap it four times to activate input rather than output to start charging. And, in fact, you can then connect a device to the Tau 2 for pass-through charging, though only something that can use the Lightning or Micro USB connector, as the USB-C connector is busy.
NFC Business Card
This uses Rolling Square’s Sherr.it technology the NFC capability shares your details with a tap by opening the Sherr.it online page that’s connected to your Tau 2. Some smartphones have this capability, but often restricted to the same brand. If your smartphone doesn’t support NFC, the same effect can be achieved using the optional QR code sticker which you can attach to the Tau 2. You should do this, so it can work in Lost Mode.
Lost Mode
This works using the QR code sticker and allows you to compose a message so that anyone who finds the Tau 2 and scans it can see how to contact you or get it back to you.
While the AirCard works with Find My on the iPhone, this doesn’t, but you can set up a message that anyone scanning the code will see.
Verdict
Rolling Square is great at innovation and this latest product is imaginative and highly effective. The Tau 2 is small (smaller than AirPods Pro, as the company points out) so it can easily slide into your pocket with your keys. The multiple cables are very convenient—the only downside is you can’t charge a device with USB-C while you’re charging the battery itself.
Overall, there’s a lot of neat tech in a small space that, on the day you forget to charge your phone when you leave the house, you’ll be glad to have in your pocket.
Tau 2 costs $39.90 from rollingsquare.com
