The Rocket Book Core is a medium-sized ring-bound planner by Rocketbook. It allows users to personalize their planner by adding written notes, drawings, and other creative elements. This planner is perfect for those who enjoy personalizing their organizational tools and prefer a flexible format that allows for freedom of expression. With its sleek design and durable construction, the Rocket Book Core is a stylish and functional choice for anyone looking to stay organized and creative.