You'll never run out of ink again with Ergosof and PenAgain Original refills. If you're a student, teacher, medical personnel or journalist and you're tired of writer's cramp, Ergosof pens will help you un-cramp your writing style and change yourlife for the better, but don't be caught out without ink. Always keep a couple of Ergosof and PenAgain Original refills handy. Each refill is simple to replace and suitable for Fisher - Triple Action, Schmidt - S600 Series, Staedtler - Multi Action, Cross - Micro Pen and Zebra - Pocket Pen4C. Replenish your favorite ergonomic as needed. These refills come in pairs and are filled with black ballpoint ink Medium/1. 0mm. Helpful for Arthritis and Ehlers Danlos Syndrome patients.