Won't bleed through paper (results could vary based on paper characteristics). Vivid color for bold, crisp writing. Perfect for coloring, writing and doodling. 0.4 mm line for fine details. Water based ink. Reusable case. Non-toxic. BIC Performance Policy (US and Canada): If you are not satisfied with the performance of this product, please return it to BIC and we will gladly replace it at no cost to you. ACMI AP: Art & Creative Materials Institute certified. Conforms to ASTM D 4236. www.bicworld.com. BICFightForYourWrite.com. Made in Korea.