This ring remembers everything so your brain doesn’t have to – and doesn’t need charging

By Abhimanyu Ghoshal

December 10, 2025

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The Index 01 is designed for discreetly capturing voice notes, and its single-use battery is meant to last you for years

Core Devices

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I’m always excited to learn what Pebble is up to, because this gadget brand – which made a name for itself with its lo-fi smartwatch – decidedly does things differently. Its latest product is an AI-enabled device that seeks to avoid the pitfalls of recent fiascos in this category, with thoughtful features and an approach to packaging you don’t often come across.

It’s called the Index 01, and it’s basically a ring for your index finger that captures your ideas as you speak into it. The concept is that it’s meant to act as external memory for your brain, while respecting your privacy and allowing you to use it discreetly with just one hand. It graces your index finger, has just one button, and includes a single-use battery that can last years.

Here’s how it works: whenever you think of something you want to remember later, press and hold down the ring’s only button and say it out loud. The Index 01 will beam that over to your phone, where your voice note will be transcribed locally, and an on-device large language model (LLM) will parse it to take actions like saving it as a note, turning it into a reminder, or setting a timer.

The device doesn’t need a subscription to work; it doesn’t even require an internet connection or to be within range of your phone to record. It’s got a bit of onboard memory, so it can capture your thoughts wherever you are and sync with your handset when you’re near it again.

Inventor Eric Migicovsky, who founded Core Devices to revive his Pebble brand and launch new products like this one, has been working on the ring for about a year now. Describing the intentions behind the Index 01’s design, he noted that it’s meant to become part of your routine, while also being unobtrusive and allowing you to be more present in your everyday life.

To that end, the ring is water resistant, so you can simply wear it all the time. And since it’s worn on your index finger, you can operate it with just one hand – unlike your phone or smartwatch that would require both hands to engage a recording function.https://www.youtube.com/embed/ArxhS4SQaP0?enablejsapi=1

We Made $75 External Memory For Your Brain!

The other big deal is the battery. While we’re used to being able to recharge virtually every other personal gadget in our arsenal, this one doesn’t have a charging port. Instead, its tiny silver oxide battery is meant to last for ‘roughly 12 to 15 hours of recording,’ which works out to two years of usage if you’re recording 3-6 second thoughts between 10-20 times a day.

Migicovsky believes that this approach – which seems like a major compromise on the surface – allows the ring to be much smaller and less expensive than it otherwise would be. Plus, there’s no charger to misplace. I’ve got a drawer full of fitness bands and other little doodads that are now unusable because their proprietary chargers have gone missing, so I can get behind this line of thinking. It’s sort of like a reasonable version of planned obsolescence: you know what you’re getting for your money, and you’re buying upfront into the notion that this thing won’t last forever.

I don’t know about you, but I’m all in on voice notes, and have been for about a decade. I run a system that lets me record ideas big and small on my phone or Wear OS smartwatch, and automatically uploads those to Google Drive; those audio files are transcribed and summarized using OpenAI’s Whisper model, and dropped into a private Notion database. It works pretty darn well, and it’s how I get a lot of my thinking done – everything from daily journaling to planning story ideas to planning motorcycle trips.

Being able to do all this more quickly would be fantastic. There are other ways to do this, and some AI hardware products promise a lot of the same thing – but the Index 01 presently seems like the most intuitive approach I’ve seen. I also like how it skips fancy features like gesture-based activation to just work reliably 100% of the time. You have to push and hold the button to record, and you can be certain it’s stopped recording when you let go.

There’s a lot that the Index 01 doesn’t do, like track health stats, count steps, light up, or even vibrate. Heck, it’s not even well suited for long voice notes, like the half-hour rambles I go on while trying to flesh out harebrained ideas for novels and screenplays. The company says that’s good because this narrow use case allows it to focus on making the ring good at the one thing it says it’ll do on the tin. I’d argue it also helps differentiate it from other similar-but-not-quite-the-same offerings like Anker’s Soundcore Work, so it simplifies the decision of whether it’s the right AI recorder thingamajig for you.

The Index 01 will retail at US$99 and can be pre-ordered now for $75; it’s set to ship next March in three colorways and eight sizes. The brand notes that you’ll be alerted via the app a month before the ring’s battery runs out, at which point you can order another and even send yours back for recycling. Given the price point and its single-use battery, this isn’t for everyone. It might well be best suited to people who already take a lot of voice notes – as opposed to someone getting into the habit for the first time – and want a better way to do it.

Find the Index 01 on Core Devices’ site.

Source: Core Devices