School Smart Dry Erase Boards are designed from a high quality melamine laminated base with a lined surface for neat and evenly spaced writing, putting down words of the week, and more. Rounded corners lend additional safety. Set of 30 makes it ideal for sharing around the classroom, doing small group discussions, or for putting onto doors or walls for announcements and reminders. One-sided design for marking; backing is non-magnetic. Whiteboard measures 9 x 12 inches with a thickness of 2.9 mm. Please test out type of whiteboard markers you are using to ensure no stains.