Sporting an ultra-slim diameter of 3.7 mm, Ohto's Minimo pen is the world's thinnest ballpoint pen (at the time of release). It comes in a holder consisting of a flexible plastic card with a pen sleeve attached. Convenience is key with this pen. The retractable mechanism allows easy one-handed operation, and the holder card makes the pen very portable.

The card (not including the pen sleeve) is the size of a Japanese business card (9.1 x 5.5 cm), which is a little larger than credit cards. The pen can be stowed on its own if desired, using the clip to secure it to papers and pockets. The pen writes well, with smooth black ink and a needle point tip that is convenient for jotting neat, small memos.

Black ink is included and is refillable.