The Rite In The Rain all-weather pen is able to write upside down, the ink will not skip, and writes through water, sweat, grease, and mud without clumping or smearing. The pressurized ink cartridge performs in temperatures from -30F to 250F, under water (up to 35ft), and at any angle. The proprietary ink and delivery system used exclusively in Rite In The Rain Pens will write without skipping in extremely wet conditions.