Extra capacity refill is designed for use with MMF Industries Jumbo Jogger Ballpoint Pens. Writes twice as long as standard refills. Writes smoothly; clearly with photocopy bank quality. Carbide ballpoints assure skip-free use. Refill will fit most desk and pocket pens. Also use in MMF Industry pens Re-Trac-To Security; Sentry and Kable Sentry pens.