E-reader with color display scores with Google Play Store and stylus: Boox Note Air4 C in a short test

Thanks to Android 13 and the Google Play Store, you can install nearly any Android app on the Boox Note Air4 C, including not only e-reader apps like Amazon Kindle but also shopping apps, note-taking tools, and much more. Onyx has reworked large parts of the Android interface and optimized it for an e-ink display. The device skips unnecessary animations and adds customizable quick settings that let you adjust screen brightness, tweak the front-light color temperature, or open the E-Ink Center.

The E-Ink Center lets you switch between higher refresh rates or better image quality, increase contrast, and fine-tune color saturation. Unfortunately, you can’t disable color entirely to take advantage of the monochrome panel’s higher resolution. The software also showed a few quirks during testing, such as stray untranslated text and the system defaulting to a Japanese keyboard layout after setup. And instead of offering one cumulative update, the device required several back-to-back updates immediately after installation.

E-Ink also displays colors - with limitations

The centerpiece of the tablet is its 10.3-inch E-Ink display based on a Kaleido 3 panel, capable of showing 4,096 colors. In color mode, the screen outputs 1,240 × 930 pixels at 150 PPI; when displaying only black-and-white content, the resolution jumps to 2,480 × 1,860 pixels. The panel is quick enough for smooth scrolling through apps and websites, but it’s still poorly suited for video playback because afterimages linger for too long.

As with all E-Ink tech, content remains faintly visible until the display performs a full refresh. This happens automatically at set intervals, but you can also trigger it manually by swiping inward from the left edge of the screen. As the photos below illustrate, the color rendering isn’t flawless. With only a limited palette to work with, the panel struggles with gradients and vivid blues and oranges. Even so, the color output is serviceable for reading comics and manga.

Passable battery life, mediocre speakers

The tablet uses a 3,700 mAh battery that charges via USB-C. Unfortunately, the USB-C port sits under the "chin," which means the Boox Note Air4 C can’t be charged while the included protective cover is closed or when the tablet is propped up with it. Thanks to the power-efficient display, you can expect up to 20 hours of eBook reading, though this varies significantly depending on front-light brightness. In standby mode, the battery loses roughly 4 percent per day.

Storage can be expanded with a microSD card, which is useful for holding music or audiobooks. The stereo speakers are fine for podcasts but fall far short of anything you’d get from an iPad Pro, so Bluetooth headphones are the better choice for music or audiobooks. The fingerprint sensor built into the power button speeds up the login process and worked reliably about four out of five times in testing.

Verdict: Versatile e-note with minor weaknesses

In testing, the Onyx Boox Note Air4 C proves to be a capable e-ink tablet. Its color display delivers acceptable results, and Android 13 with full Google Play Store access makes it compatible with virtually every reading app. It can also handle audiobooks, music, and podcasts without issue.

That said, a few shortcomings stand out. Minor software hiccups popped up during testing, the limited color rendering and persistent afterimages make the device poorly suited for video streaming, and both the stereo speakers and fingerprint sensor could benefit from improvements.

The Boox Note Air4 C is available on Amazon (Germany) for €529. The compatible Pen Plus stylus is included, while the flip case is sold separately for about €50.

Translator’s note: In the US, the device is available on Amazon for about $499.99.