Post-it® Flex Write Surface Sheets are a 9.1 in x 9.1 in. dry erase whiteboard you can use with dry erase AND permanent markers to help track due dates, to do’s, agendas, homework assignments, and more. Go ahead use permanent markers so there is less chance of accidental smearing or erasing, Create a calendar outline in permanent marker, then use dry erase markers for adding individual day tasks. Wipe off dry erase markers, while the calendar created in permanent marker stays in tact. When it's time to change, the permanent marker wipes away with just water. This smaller size version allows you the flexibility to instantly transform cabinets, walls, desks and work surfaces into a whiteboard and the freedom to write with permanent markers without stains.