Writes through: the permanent ink writes through water, grease, and mud without clumping or smearing.
Pressurized cartridge: the all-weather cartridge is pressurized, functioning in temperatures from -30F to 250F, underwater (up to 35 ft), and at any angle.
Proprietary ink: the ink and delivery system used exclusively in refills will write without skipping in extremely wet conditions, performing far better than other comparable all-weather pens.
Ink delivery: tiny pockets in the pen's tip deliver ink in the harshest conditions without letting water or air back into the cartridge