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TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black emergency keyring power bank with integrated charging cables attached to a keyring with two keys and. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact dark gray power bank with 2000mAh battery, keyring hook, and multi-port cables. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black charging dock with attached cable, shown held in hands near wall and laptop charging setups. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black keyring power bank held near face with silver ring on hand. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - TAU® 2 Agave Green emergency keyring power bank shown with compatible devices and connection types icons. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black TAU® 2 emergency keyring power bank shown attached to keys. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black emergency keyring power bank with removable QR code sticker on top. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black emergency keyring power bank with built-in NFC digital business card feature, attached to keys. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact rectangular power bank in matte black with rounded edges and integrated keyring loop on a dark textured background. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact gray keyring power bank with built-in USB, USB-C, and Lightning connectors attached to keys. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact white TAU® 2 power bank with keyring hook and release system, smaller than AirPods Pro. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Hand placing a compact black charging dock with a cable near a white wall outlet and a silver laptop, showing versatile. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact gray emergency keyring power bank held near face with rounded edges and smooth finish. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact rectangular black emergency keyring power bank with USB-C and lightning ports. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black TAU® 2 power bank attached to a keyring with integrated charging cables and a small LED indicator. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black TAU® 2 emergency keyring power bank with removable QR code sticker being applied. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black keyring power bank attached to keys next to smartphone displaying NFC digital business card interface. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact rectangular power bank keyring in matte black with rounded edges and subtle logo, displayed on black textured. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black emergency keyring power bank with integrated charging cables attached to a keyring with two keys and. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact dark gray power bank with 2000mAh battery, keyring hook, and multi-port cables. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black charging dock with attached cable, shown held in hands near wall and laptop charging setups. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black keyring power bank held near face with silver ring on hand. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - TAU® 2 Agave Green emergency keyring power bank shown with compatible devices and connection types icons. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black TAU® 2 emergency keyring power bank shown attached to keys. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black emergency keyring power bank with removable QR code sticker on top. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black emergency keyring power bank with built-in NFC digital business card feature, attached to keys. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact rectangular power bank in matte black with rounded edges and integrated keyring loop on a dark textured background. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact gray keyring power bank with built-in USB, USB-C, and Lightning connectors attached to keys. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact white TAU® 2 power bank with keyring hook and release system, smaller than AirPods Pro. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Hand placing a compact black charging dock with a cable near a white wall outlet and a silver laptop, showing versatile. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact gray emergency keyring power bank held near face with rounded edges and smooth finish. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact rectangular black emergency keyring power bank with USB-C and lightning ports. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black TAU® 2 power bank attached to a keyring with integrated charging cables and a small LED indicator. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black TAU® 2 emergency keyring power bank with removable QR code sticker being applied. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black keyring power bank attached to keys next to smartphone displaying NFC digital business card interface. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact rectangular power bank keyring in matte black with rounded edges and subtle logo, displayed on black textured. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black emergency keyring power bank with integrated charging cables attached to a keyring with two keys and. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact dark gray power bank with 2000mAh battery, keyring hook, and multi-port cables. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black charging dock with attached cable, shown held in hands near wall and laptop charging setups. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black keyring power bank held near face with silver ring on hand. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - TAU® 2 Agave Green emergency keyring power bank shown with compatible devices and connection types icons. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black TAU® 2 emergency keyring power bank shown attached to keys. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black emergency keyring power bank with removable QR code sticker on top. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black emergency keyring power bank with built-in NFC digital business card feature, attached to keys. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact rectangular power bank in matte black with rounded edges and integrated keyring loop on a dark textured background. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact gray keyring power bank with built-in USB, USB-C, and Lightning connectors attached to keys. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact white TAU® 2 power bank with keyring hook and release system, smaller than AirPods Pro. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Hand placing a compact black charging dock with a cable near a white wall outlet and a silver laptop, showing versatile. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact gray emergency keyring power bank held near face with rounded edges and smooth finish. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact rectangular black emergency keyring power bank with USB-C and lightning ports. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black TAU® 2 power bank attached to a keyring with integrated charging cables and a small LED indicator. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black TAU® 2 emergency keyring power bank with removable QR code sticker being applied. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black keyring power bank attached to keys next to smartphone displaying NFC digital business card interface. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact rectangular power bank keyring in matte black with rounded edges and subtle logo, displayed on black textured. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black emergency keyring power bank with integrated charging cables attached to a keyring with two keys and. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact dark gray power bank with 2000mAh battery, keyring hook, and multi-port cables. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black charging dock with attached cable, shown held in hands near wall and laptop charging setups. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black keyring power bank held near face with silver ring on hand. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - TAU® 2 Agave Green emergency keyring power bank shown with compatible devices and connection types icons. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black TAU® 2 emergency keyring power bank shown attached to keys. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black emergency keyring power bank with removable QR code sticker on top. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black emergency keyring power bank with built-in NFC digital business card feature, attached to keys. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact rectangular power bank in matte black with rounded edges and integrated keyring loop on a dark textured background. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact gray keyring power bank with built-in USB, USB-C, and Lightning connectors attached to keys. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact white TAU® 2 power bank with keyring hook and release system, smaller than AirPods Pro. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Hand placing a compact black charging dock with a cable near a white wall outlet and a silver laptop, showing versatile. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact gray emergency keyring power bank held near face with rounded edges and smooth finish. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact rectangular black emergency keyring power bank with USB-C and lightning ports. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black TAU® 2 power bank attached to a keyring with integrated charging cables and a small LED indicator. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact black TAU® 2 emergency keyring power bank with removable QR code sticker being applied. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact charcoal black keyring power bank attached to keys next to smartphone displaying NFC digital business card interface. - Rolling Square
TAU® 2 - Emergency keyring power bank - Mercury Black - Compact rectangular power bank keyring in matte black with rounded edges and subtle logo, displayed on black textured. - Rolling Square

TAU® 2 - Emergency keyring power bank

$39.90
Color: Mercury Black
Ice Gray
Mercury Black
Quantity:
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Designed in Switzerland

TAU 2 is our ultra-compact emergency power bank designed to stay charged and ready at all times.

🔋 Always Ready
Recharges automatically from its magnetic dock, so it’s full whenever needed.

⚡️ Quick Power Boost
Provides an average 30% battery increase for phones in just minutes. Completely charges smaller devices like earbuds. 🔌 Integrated Connectors
Built-in USB-C, and Lightning + Micro USB connector to ensure universal compatibility.

🧲 Magnetic Dock
Charges TAU 2 and securely holds your keys simultaneously.

🔑 Keyring Size Design
Lightweight and built for everyday carry.

TAU 2 is our ultra-compact emergency power bank designed to stay charged and ready at all times.
READ MORE
PRODUCT INFO


TAU® 2 | 3in1 emergency keyring power bank
Introducing TAU 2 - your trusty, always-charged, universal keyring emergency power bank. Never again will you have to suffer the indignity of your phone giving up on you at the worst possible moment. You’ll no longer need to carry bulky power banks to make important calls 📞, pay with your phone 💳, or use GPS maps 🗺️, even towards the end of the day when your phone's battery is running low. 

You'll never forget to re-charge it
With TAU 2, forgetting to charge your power bank is a problem of the past. Charge your TAU 2 just by putting away your keys the way your mother told you. We even took the time to give you a quick and easy way to set up its charging dock on a desk, on a wall, or even the door side table. Now your power bank is always fully charged and within reach right alongside your keys, eliminating the frustration of a dead battery when you're on the go. Your keys are always in the right place and your power bank is always charged. 🔑🔋

Your keys' new best friend
TAU 2 is so small and compact that it easily fits on your keyring without adding any bulk. The fact that it hooks on your keys means that so long as you have your keys you also have power. The fact that it's always charged means that the Charging Dock will serve as your new tidy place for keys, seamlessly recharging TAU 2 without you even noticing, so it's ready for your next departure. Say goodbye to carrying around a separate power bank with cables in your bag or pocket, or worse, forgetting to bring them with you!

Battery capacity
TAU 2 may not immediately captivate with its 2000mAh capacity, but it's truly impressive. 🔍 We tested smartphones from major processor producers, revealing three battery improvement ranges: small-battery phones gained up to 54%, mid-battery phones up to 35%, and large-battery phones up to 28%. We calculated these results conservatively, considering battery consumption data from producers, reviewers, and real-life tests, factoring in dispersion and performance decrements due to background apps. Visit the "battery capacity" section on our Kickstarter's TAU 2 page for a detailed understanding of our tests and results!

Key features (3in1)

  • Charge USB-C devices
  • Charge Lightning devices
  • Charge Micro USB devices

    Extra features

    • Included NFC tag for Digital ID and Lost mode
    • Optional adhesive QR Code stickers for Digital ID and QR Lost mode
    • Pass-through charging (USB-C as input, Lightning/Micro USB as output)
    • Quick-release keyring hook


    Designed with love     ❤️️ in Switzerland

      TECHNICAL SPECIFICATIONS

      Compatibility

      Lightning (iPhone, iPad, AirPods)
      USB-C devices
      Micro USB devices

      Technical

      Size: 56*x43x19mm (2.2*x1.7x0.7in) *Dimension without hook. Dimension with hook: 63mm / 2.5in
      Weight: 50g / 1.7oz
      Capacity 2000 mAh
      Holdable weight: 690gr / 24oz

      WHAT'S IN THE BOX

      TAU® 2 Power bank

      TAU® 2 Dock with USB-C integrated cable
      Nano suction double-sided layer
      User manual
      Eco-friendly packaging

      REVIEWS
      AS SEEN ON
      9to5Mac Wired AppleInsider CBS News Cult of Mac Gizmodo Entrepreneur Forbes Tom’s Guide Android Police 9to5Google Gear Patrol The Verge Digital Trends ZDNET Android Central
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      TAU® 2 - Emergency keyring power bank
      $39.90
      quantity
      quantity
      ADD TO CART
      ADD TO CART
      $39.90

      🤔 QUESTIONS?

      Yes, TAU 2 covers pretty much everything. It has a built-in USB-C connector plus a patented Dual connector combining Lightning and Micro USB, so it charges USB-C Android phones, iPhone 15 and up, iPhone 14 and below, iPads, AirPods, and older Micro USB devices.
      On average about +30%, which translates to roughly +4.2 hours of call time or +3.2 hours of internet browsing based on 2023 phone tests. Small-battery phones see the biggest boost, up to 54%, while large-battery phones gain around 28%.
      No cable needed day to day. Just rest your keys on the magnetic Charging Dock and TAU 2 tops itself up automatically, the dock only needs its integrated USB-C cable plugged into an outlet once it's mounted.
      Not really, it's smaller than an AirPods Pro case at 56x43x19mm (63mm with the hook) and weighs just 50g. It attaches via a quick release hook and can support up to 690g of keys.
      You get the TAU 2 power bank, the charging dock with its integrated USB-C cable, a repositionable nano suction adhesive layer for mounting the dock, a user manual, and eco-friendly packaging.
      Yes, the dock comes with a repositionable nano suction double-sided adhesive layer, so you can stick it to a wall or desk and reposition it as needed.
      TAU 2 includes a Lost Mode feature: whoever finds your keys can tap the built-in NFC tag and get a prompt to call you directly. Optional QR code stickers are also available for Digital ID and QR-based Lost Mode.
      Yes, TAU 2 supports pass-through charging, using its USB-C port as input while outputting through the Lightning or Micro USB connector at the same time.
      TAU 2 comes with a 2 year warranty valid worldwide.
      It's a 2000mAh battery, which is designed for emergency top-ups rather than a full recharge. In real-world testing it still delivers an average +30% boost to your phone's battery, enough for a few extra hours of calls or browsing when you need it most.
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      Customer Reviews

      Based on 177 reviews
      72%
      (128)
      14%
      (24)
      10%
      (18)
      2%
      (4)
      2%
      (3)
      T
      TechieTom
      Just got mine, initial impressions good

      My charger arrived and looks good. Works as expected.

      D
      Daniel
      Perfect little lifesaver

      This compact power bank is fantastic, carry it on my keys everywhere I go. The magnetic charger setup is effortless, and I can quickly boost my phone's battery in a pinch. Rolling Square customer support is excellent as well.

      L
      Liam
      Customer support handled my issue quickly

      I contacted customer service with a minor charging issue, and they resolved everything quickly and politely.

      A
      Alex
      Great experience overall

      Backed their recent crowdfunding project, and I'm really impressed. Quick responses, timely delivery, and the build quality is top-notch. Loved it so much I ended up buying a second one.

      123

      READ THE GUIDES

      From our editorial team — practical guides where this product fits in.

      The best iPhone chargers in 2026, featuring the Rolling Square Supertiny 65W GaN charger
      Guide Jul 16, 2026

      The Best iPhone Chargers in 2026: Wall, Portable, and Cable Picks

      By Lorenzo Filiberto Ferraris · Co-founder at Rolling Square · Updated July 16, 2026 The best iPhone charger for most people in 2026 is ...

      Lorenzo Filiberto Ferraris Read →
      How to charge a power bank, step-by-step guide with the Rolling Square TAU 2 keyring power bank
      Guide Jul 15, 2026

      How to Charge a Power Bank: Step-by-Step Guide

      By Lorenzo Filiberto Ferraris · Co-founder at Rolling Square · Published July 15, 2026 To charge a power bank, plug a USB-C cable into t...

      Lorenzo Filiberto Ferraris Read →
      Best wallet tracker cards 2026 buyer's guide on dark slate with wallet, keys and phone, Rolling Square
      Guide Jun 26, 2026

      Best Wallet Tracker Cards in 2026: 7 Cards Tested and Ranked

      The best wallet tracker card in 2026 is one that works with both Apple Find My and Android Find Hub, recharges on any Qi pad, and disappe...

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