The Xteink X4 and smaller X3 e-readers are discounted to $55.20 (regularly $69) and $63.20 (normally $79), respectively, as part of Amazon’s Prime Day promotions this week. Both e-readers are significantly smaller and more pocketable than any of the Kindle and Kobo models currently available, and feature magnetic mounts so they can be stuck to the back of MagSafe-compatible smartphones. The bundled software is a little rough around the edges, but the versions Amazon is selling can both be easily upgraded to the free CrossPoint Reader firmware featuring a more polished user interface.

In our hands-on with the X4, we liked that the e-reader features several buttons that are used to turn the pages of an ebook, but struggled with navigating its sometimes challenging bundled software using buttons in lieu of a touchscreen. Battery life is excellent, and the e-reader provides several different ways to load up books and other documents, but keep in mind you won’t have access to a dedicated online bookstore like Kindles and Kobos feature.

The X3’s functionality is similar to the X4, but with a smaller design, an improved button layout, and broader compatibility with smaller smartphones featuring magnetic mounts on the back. It’s even easier to stash in a small pocket, but the X3’s dependence on a proprietary magnetic USB charging cord could be a deal breaker for those prone to losing cables.