What formats can it read?

EPUB, PDF, and TXT. You transfer files over Wi-Fi, and they open on the 3.97-inch E-Ink screen.

Does it have a backlight?

No. E-Ink has no backlight. You read by the light already in the room, the same way you read printed paper, which is what keeps glare and eye strain down.

Does it need the phone to read?

The hub has its own screen, 4 GB of local storage, and its own battery, so reading happens on the hub itself rather than on the phone's display. You use the phone to send files across over Wi-Fi.

How long does the battery last?

The 1100 mAh battery is independent from the phone. It gives 30+ days of standby, and you charge it over USB-C without touching the phone's charge.

E-Ink Reading

An E-Ink reader for the back of your phone

A snap-on 3.97-inch E-Ink screen that sits on the back of the phone you already carry. Read EPUB, PDF, and TXT with no glare and no backlight.

Why E-Ink

Why E-Ink beats your phone screen for reading

A phone screen is built to grab attention. That is the wrong tool for a long read. E-Ink is different: the surface reflects light the way paper does, so there is no backlight shining into your eyes and no glare fighting you in bright rooms or outdoors. Text stays still and quiet, closer to the page than to a feed. And because the Reetle hub carries its own battery, the time you spend reading is not time you spend draining the phone in your hand.

What changes when you read on E-Ink

No backlight in your eyes.E-Ink has no backlight at all. You read by the light already in the room, the same way you read paper.
No glare, indoors or out.The matte surface holds up in sunlight and under office lighting instead of turning into a mirror.
Its own battery.The hub runs on a separate 1100 mAh cell, so reading does not drain the phone and the phone does not charge the hub.
Quiet by design.A reading screen on the back of the phone, away from the notifications on the front.

The category

The ways to add E-Ink to a phone

If you want a paper-like screen alongside your phone, there are a few broad routes, each with its own trade-offs. This is the high-level map, not a scoreboard.

Three broad routes

Dedicated snap-on readers.A small E-Ink accessory that attaches to the phone you already own. You keep one device in your pocket and gain a reading surface. The trade-off is that it is an add-on with its own screen size and format support to check.
E-Ink phone monitors.A separate E-Ink display that pairs with the phone to mirror or extend it. Flexible, but it is a second screen to carry, set up, and keep charged.
Full E-Ink phones.A phone where the whole display is E-Ink. The most committed option, and it means giving up the colour, speed, and app experience of a normal phone screen for everything, not just reading.

Where Reetle fits

Reetle: reading plus AI capture and to-do in one hub

Reetle is a dedicated snap-on hub, so the E-Ink reader is only half of it. The same screen on the back of your phone also handles AI meeting capture, with transcripts and summaries in the app, and an always-on smart to-do that stays in front of you through the day. One piece of hardware, reading and capture together, instead of a single-purpose reader.

One hub, more than one job

Read.EPUB, PDF, and TXT on the 235 PPI E-Ink screen, one tap from the phone.
Capture.Tap to record a meeting; sync to the app for transcription in 100+ languages, AI summaries, action items, and mind maps.
Stay on track.An always-on smart to-do lives on the back screen, visible at a glance without unlocking the phone.
Keep it private.Private Mode keeps sensitive recordings on the device rather than in the cloud.

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Specs

Specs that matter for reading

The details that decide whether a screen is comfortable to read on, and how long you can read before you have to charge it.

Reading and hardware

Display.3.97-inch E-Ink touchscreen, 480 x 800 pixels, 235 PPI, black and white.
Backlight.None. E-Ink is reflective; you read by ambient light.
Formats.EPUB, PDF, and TXT.
Battery.1100 mAh, independent from the phone. 30+ days of standby; it does not drain or charge the phone.
Storage.4 GB local storage.
Charging.USB-C, charged separately from the phone.
Connectivity.Bluetooth 5.0 and Wi-Fi file transfer.
Attachment.Four-corner lock with a side-release groove, tempered glass, recessed screen, anti-fingerprint finish.
Size and weight.55 g, 5.4 mm thick.
Compatibility.Compatible iPhones; the full list is published at launch.

FAQ

Reading questions, answered

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See the reader in context.

The E-Ink reader is one side of the Reetle hub. See the full product, or read how people use it day to day.

Reserve pre-order or see how people use Reetle

Snap-on AI E-Ink hub for smartphones. Read, capture, and stay on track from the back of your phone.