So, you’re looking at the Onyx Boox Note Air 4 C. Honestly, I get it. It looks like the dream device on paper. A 10.3-inch color screen that doesn't fry your retinas? Check. Full access to the Google Play Store so you aren't trapped in a Kindle-shaped prison? Check. It’s thin, it’s metal, and it’s got that "I’m a serious professional who also likes comic books" vibe.
But here’s the thing. Most people buy these things expecting an iPad with a paper screen. It isn’t that. Not even close. If you walk into this expecting buttery-smooth 120Hz scrolling and TikTok-ready colors, you’re going to be frustrated within five minutes of unboxing it.
The Onyx Boox Note Air 4 C is a tool, not a toy. It's a very specific, somewhat quirky evolution of the Note Air 3 C. It's faster, sure, but it still plays by the rules of E Ink physics, which means you’re dealing with ghosting, muted colors, and a battery that actually cares if you leave the Wi-Fi on.
The Screen Reality Check
Let’s talk about the Kaleido 3 display. This is the heart of the Onyx Boox Note Air 4 C, and it’s the most misunderstood part of the whole package. On Amazon or the Boox website, the renders make the colors look like a high-end magazine. In your hands? It’s more like a newspaper from the 1990s.
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That’s not a diss. It’s just how the tech works.
The device has two resolutions happening at once. When you’re reading black-and-white text, it’s a crisp 300 PPI. The moment you add color—like a red highlighter or a comic book page—that resolution drops to 150 PPI. It’s a trade-off. Because there’s a color filter layer sitting on top of the E Ink, the screen is naturally darker than a standard Kindle. You’ll find yourself using the frontlight way more often than you’d think, even in a well-lit room.
One of the big "upgrades" Onyx touts for the Note Air 4 C is the "improved" Kaleido 3 screen. In reality, it’s mostly about the background being a slightly "whiter" shade of gray and the refresh rates being a bit snappier. Does it look better than the 3 C? Yeah, a bit. Is it a night-and-day transformation? No.
Performance: 6GB RAM Actually Matters
Onyx bumped the RAM from 4GB to 6GB in this model. Two gigabytes doesn’t sound like much in the world of smartphones, but for an E Ink tablet running Android 13, it’s a lifeline.
I’ve spent enough time with the older Note Air 3 C to know the "sluggishness" struggle. On the Onyx Boox Note Air 4 C, multitasking actually feels... okay. You can have a heavy PDF open in NeoReader while keeping Slack and Spotify running in the background without the whole thing gasping for air.
- Processor: It uses a Snapdragon 750G. It's an octa-core chip that won't win any races against an M4 iPad, but it handles the "Boox Super Refresh" (BSR) technology well.
- Refresh Modes: You’ve got options like "HD" (best for reading) all the way up to "Ultrafast" (you can technically watch YouTube, but why would you?).
- Storage: 64GB internal, which fills up fast if you’re a comic collector, but the microSD slot is the real MVP here.
Most people don't realize how much the BSR technology drains the battery. If you leave the device in "Ultrafast" mode, you aren't getting weeks of juice. You’re getting maybe two or three days.
Writing on the Onyx Boox Note Air 4 C
Writing on this thing feels great. Honestly, it's one of the best parts. The screen has a pre-applied film that adds just enough friction to keep the stylus from sliding around like a puck on ice.
The latency is almost non-existent in the native Notes app. If you use third-party apps like OneNote or Evernote, there’s a bit more lag, but Boox has been working on "optimizations" for those apps for years. It’s usable now, whereas three years ago it was a disaster.
But here is a weird detail: the pen that comes in the box is... fine. Just fine. It’s light and feels a bit plasticky. If you’re serious about note-taking, you’ll probably end up buying a Lamy Al-Star EMR or a Staedtler Noris Digital within a month. The magnet on the side of the tablet is strong, but the pen still likes to go on adventures in the bottom of your bag if you don't have a case with a flap.
The Software: Android 13 is a Double-Edged Sword
Running Android 13 on the Onyx Boox Note Air 4 C is what makes it better than a ReMarkable 2 for many people, but it’s also what makes it more annoying.
The ReMarkable is a "focused" device. It does one thing. The Boox does everything, which means you have to spend two hours in the settings menu just to get it to act the way you want. You have to tell the device how to handle "ghosting" for every single app. You have to tweak the DPI settings so the text doesn't look like pixelated mush in the Kindle app.
It’s an enthusiast’s device. If you love tinkering, you’ll be in heaven. If you just want to open a notebook and write, you might find the "Tablety" UI a bit much.
What No One Tells You About the Battery
"E-readers last for a month!"
Not this one.
The Onyx Boox Note Air 4 C has a 3,700mAh battery. That’s smaller than most modern phones. Because it’s powering a color screen, a BSR graphics chip, and full-blown Android, the battery life is "tablet-lite" rather than "e-reader-heavy."
If you’re a student taking notes for six hours a day with the backlight on and Wi-Fi connected, you’ll be charging this every other night. If you put it in Airplane Mode and just read novels, you can get a week or two. It’s important to manage your expectations here.
Is it Worth the Upgrade?
If you already own a Note Air 3 C, the answer is probably no. The jump from 4GB to 6GB RAM and Android 12 to 13 is nice, but it doesn't fundamentally change what the device is.
However, if you’re still rocking an old monochrome Note Air or you’re coming from a basic Kindle and want to start marking up PDFs in color, the Onyx Boox Note Air 4 C is currently the best 10-inch color E Ink device on the market. It beats the ReMarkable Paper Pro in versatility, and it beats the Bigme devices in software polish.
Actionable Steps for New Owners:
- Disable the "Boox AI Assistant" if you don't use it; it just clutters the interface.
- Set up Per-App Refresh Rates. Set your reading apps to "HD" and your web browsers to "Fast."
- Buy a Matte Screen Protector if you want even more tooth for writing, though the factory film is decent.
- Use the "Freeze" Feature. Android apps love to run in the background. Use the built-in app freezer to stop Instagram or Gmail from killing your battery while you're trying to read a book.
- Get a MicroSD Card. Don't rely on the 64GB internal storage if you plan on downloading large PDF textbooks or high-res comics.
The Onyx Boox Note Air 4 C isn't perfect, and it isn't an iPad replacement. It's a high-end digital legal pad that happens to have a Google Play Store and a splash of color. Treat it like that, and you'll love it.
Data based on official manufacturer specifications from Onyx International and real-world performance benchmarks from 2024-2025 product cycles.