With an innovative ink delivery system, the Rite in the Rain All-Weather Durable Pen is one of the most versatile pens in the world. A pressurized cartridge delivers a steady stream of ink at any angle and performs in temperatures from -30 to 350°F. Rite in the Rain's proprietary ink formula works as hard as you do, writing through grease, water, sweat, and mud without skipping a beat. The All-Weather Durable Pen performs ideally with all Rite in the Rain notebooks and paper (sold separately).