These hard-cover sketch books feature high performance, pH neutral, lignin- and chloride-free paper. The extra heavy-weight 270 gsm paper has a white cold-press surface, and is suitable for all dry media and ink. With both internal and surface sizing, it will accept light washes, wet media and watercolor as well. The covers are made with extra heavy-weight binders' board that is tough and resistant to warpage. The hard-bound books contain 26 sheets and the wire-bound books contain 25 sheets.