Pen UNO Titanium is paragon of minimalism- a pen designed for architects and designers. It is the result of liberating a pen of all unnecessary components. Its grip section doubles as twisting cap that moves up and down to protect or expose the pen tip. With only 5mm in diameter, UNO is one of the slimmest pens ever manufactured. Despite this, it is very comfortable to use because its grip section is as wide as a traditional wooden pencil.