Some information on PlanetSafe's Dry-Erase products. All BlueLine products have a soft tinted 1/2" spaces grid to help the user write straighter and neater. Our BlueLine Posters (paper poster - non mounted) are manufactured with the best Dry-erase material available. Dry-Erase can be left on the surface for extended periods without leaving ghost images or stains. Be aware that lower quality dry-erase markers may not wipe clean. Our markers and expo always work great (Staples too). Colored dry-erase may leave ghosting if left on for extended periods (weeks) so wiping clean after a few days is recommended. Wet-Erase will stain. This surface is designed for dry-erase. If at any time you want to clean the surface use Expo Dry-Erase cleaner and then wipe off the surface with a damp paper towel to wipe the cleaner residuals off.