Pentel Rolling Writer Roller Ball Pen, Stick, Medium 0.8 mm, Black Ink, Black Barrel, Dozen

A 0.8mm rollerball pen with a cushioned tip that writes the same line whether you bear down or barely touch the page, and an ink reservoir big enough to write over a mile before it runs out. Sold as a dozen, so running out isn't something you plan around.

This is the pen for a desk that goes through pens fast, not because they're disposable, but because there's always a fresh one in the drawer instead of a search for the last working one.