Xteink's X3: A Credit-Card-Sized E-Reader That Sticks to Your Phone

A Chinese company called Xteink has released a new device called the X3—essentially a small e-reader that magnetically attaches to the back of your smartphone. The device costs $79 and launched in early 2024. The idea is simple: people who like reading on e-ink screens (which are easier on the eyes than phone displays) can now get that experience without carrying around a separate e-reader.

What Is It, and How Does It Work

The X3 is about the size of a credit card—3.7 inches diagonally—and it sticks to your phone using magnets. It works with phones that have either Qi2 or Apple MagSafe (the magnetic attachment system Apple introduced in 2020). If your phone doesn't have built-in magnets, Xteink includes two small magnetic rings you can stick on.

The device has a small 650 mAh battery, similar in capacity to what you might find in a wireless earbud. According to Xteink's specs, it lasts 10 to 14 days if you read 1 to 3 hours per day. You charge it using a proprietary magnetic cable—not the standard USB-C you're used to—so you'll need to carry device-specific charging hardware when traveling.

The physical buttons are straightforward: a power button and dedicated page-turn buttons. There's also a gyroscope sensor that lets you flip pages by shaking the device, handy when it's mounted on your phone.

Software and Content: A Closed Approach

The X3 only works with Xteink's own app. You cannot use other reading apps (like Kindle, Apple Books, or Kobo) or sideload your own files. This means you're limited to whatever content and formats Xteink officially supports.

Xteink describes its mission as "developing intuitive reading experiences, encouraging continuous learning and exploration, and building a community of thoughtful readers," according to its mission statement. However, the closed software approach does limit your flexibility if you have books or documents in formats the company doesn't support.

Form Factor Trade-Offs

Xteink also sells a larger model, the X4, for $69. The X4 is a more traditional e-reader at 4.9 millimeters thick and 74 grams. The X3's magnetic attachment concept solves a particular problem: you get the benefits of an e-ink screen (low power consumption, easy on the eyes) without carrying a separate device. But there is a catch—your phone screen will be partially covered while you're reading.

The magnetic attachment concept is not entirely new. When Apple introduced MagSafe in 2020, it opened the door for other companies to attach things magnetically to phones. We saw a wave of magnetic phone accessories come to market, and manufacturers keep finding new uses for the technology that Apple didn't originally have in mind.

Practical Limitations Worth Considering

The 3.7-inch screen is much smaller than a typical e-reader, which usually ranges from 6 to 10 inches. This matters if you're reading books with small print or complex layouts—the tiny screen makes that harder to read comfortably.

The 650 mAh battery is decent for light reading, but the claimed 10- to 14-day lifespan assumes you're not a heavy reader. If you read several hours a day, you might see shorter battery life.

The proprietary charging cable is also a potential weak point. If you travel without that specific cable, you cannot charge the device. Standard USB-C would have been more convenient. One other thing worth keeping in mind: the magnetic attachment's reliability depends on your phone case. A thick protective case might interfere with the magnets, or the magnetic connection could weaken over time.

Price and Comparison

At $79, the X3 costs more than some basic e-readers but less than full-featured models from Amazon, Kobo, or other major manufacturers. You're paying extra for the specialized form factor and magnetic mounting, not for better display technology or processing power.

The X3 competes on convenience—you get an e-ink reading experience without a separate device—rather than on reading quality. If you want the best possible screen, the widest selection of books, or a larger display for extended reading sessions, a traditional e-reader is the better choice.

From a broader view, the X3 is an interesting experiment in fitting an e-reader into a smaller form factor, but it is not a breakthrough in e-reader technology. The magnetic phone attachment does address a real frustration people have with carrying multiple devices, but the trade-offs in screen size and software options mean it will only appeal to a specific type of user. Whether this device catches on will likely depend on how well the magnets hold up over time, how often Xteink updates its software, and whether the company expands its library of available books and formats.