If you’ve ever tried to cram humanity’s knowledge of mathematics onto a single cheat sheet, this selection guide will be useful to you. American pens and pencils tend to weigh in at a hefty 0.5 mm, turning inviting surfaces like calendar squares, filing cabinet labels, and book margins into dense war zones.

Luckily, the Japanese have pioneered all things compact and small, and they’ve got you covered with pens as small as 0.18 mm. 0.18 mm! That’s small enough to write on a grain of rice, if you’re so inclined. Oh, and they also have 0.25 mm, 0.28 mm, 0.3 mm, 0.38 mm, and 0.4 mm... because the Japanese are like that.