The Sakura Microperm pen is fantastic for all those challenging surfaces we come across, including plastic, metal, glass, photos, film, CDs, and so on. The quick-drying, waterproof ink is permanent on most surfaces and is resistant to most household cleaners. (However, alcohol-based cleaners do remove the ink from non-porous surfaces.) The ink also meets ACMI non-toxicity standards. The durable tip does not split, and the fine point is great for writing in small spaces or creating precise, detailed drawings.