Rocketbook Cloud Cards are reusable index cards built for the digital age. Like all other index cards, these are 3” x 5”. Unlike all other index cards, Cloud Cards work with the Rocketbook app to be automatically turned into a digital pop-quiz for late night learning or practicing a presentation. Remember, the innovative synthetic paper allows you to write smoothly with a Pilot FriXion pen, then magically wipe your pages clean with a damp cloth to reuse again and again. With lines on one side and a dot-grid on the other, Cloud Cards conform to your note-taking needs. So get your head out of the clouds, and into the future of index cards!