Rite in the Rain All-Weather Pen ink refill cartridges will write for a considerable amount of time. When your ink finally runs out, this refill will get your trusty All-Weather Pen back into the field. Don't worry about the refill fitting your pen; all Rite in the Rain All-Weather Pens use the same pen refill style. This pen refill is 3 1/2in long with black ink.