Clearprint Vellum Pads feature 50 sheets each of smooth 16 lb. 1000H transparent vellum. Pen and pencil lines come out sharp and clean without feathery edges or ghosting. It retains strength, stability, transparency and printing qualities under exposure to heat, light and atmosphere. The paper will not become yellow, opaque or brittle with age. It retains the qualities of the traditional 100% cotton vellum while featuring non-repro blue grids in a wide variety of gradations. Grid sizes are measured by the number of boxes per inch. The lines will not reproduce when used with traditional graphic arts cameras or copiers.