Sakura bright white classic 1 piece medium point pen set is great for writing on dark paper. It is waterproof. The line width is .8mm. Use for almost any permanent writing application. Journals and scrapbooks. Letters, notes and memos. Legal documents. Recipes and grocery lists. Technical qualities are archival quality ink, consistent ink flow to the last stroke, will not smear or feather when dry, waterproof and chemical proof, fade resistant, does not bleed through most papers, meets astm and acmi nontoxicity standard ap seal, not recommended for use on fabrics intended to be washed, on food service or ceramics that are washed, and not evaluated for cosmetic use on skin.