The Uni Power Tank looks may look like an ordinary plastic pen, but don’t be fooled—this retractable pen truly is a tank that can power through just about any writing situation. It was one of the few “regular” pens we tested to write well on labels. Both the 0.7 mm and the 1.0 mm tip sizes dried within 10 seconds on our office labels and almost instantly on ordinary copy paper, so you can be sure that your notes will be smudge free.

The Power Tank contains pressurized ballpoint ink that defies gravity to keep writing at even the oddest angles. This lets you easily make notes wherever you are. And since pressurized ink will write on paper that is already wet in addition to being waterproof, there’s no need to worry about the effect any mishaps will have on your charting.

The Uni Power Tank’s firm, lightly textured rubber grip is easy to clean and comfortably anti-slip. The grip is slightly thicker than most single-color pens, but it’s still thin enough to switch between multiple colors held in the same hand.

There are two drawbacks to this pen: it has only a standard clip with no lanyard hole, and it only comes in black, blue, and red. If you’re a lanyard pen kind of nurse and don’t mind a thicker barrel, consider the Tombow AirPress. It boasts the same pressurized ink benefits as the Power Tank plus a sturdy, spring-loaded wire clip and lanyard hole. Although each pen only comes with black ink, its refills are available in four colors. For those who’d like to to venture beyond the standard ink colors, keep reading to see our other picks.