Our Hive | Pro notebook is full of helpful conversions commonly used by designers, architects, carpenters, cabinet makers, and many others. These charts include the decimal equivalents of inches and millimeters, inch to millimeter conversions, square foot and area calculators, weight conversions, and more. All of our notebooks are made from stone paper. This makes them completely waterproof and tear resistant. We recommend using pencils, ballpoint pens, and felt tipped markers. Wetter inks, such as gel pens, are not recommended.