The Rite in the Rain All-Weather Black Ink Olive Pen has permanent ink that writes through water, grease, and mud without clumping or smearing. The all-Weather cartridge is manufactured in the USA by Fisher Pen Company. The pressurized ink writes in temperatures from -30F to 250F, under water (up to 35 ft), and any angle. The ink and delivery system used exclusively in Rite in the Rain Refills will write without skipping in extremely wet conditions far better than other comparable weatherproof pens. Tiny pockets in the pen's tip will deliver ink in the worst conditions without allowing water or air back into the cartridge.