The Kaweco blue M ballpoint pen refill ensures a clean and continuous ink flow with great durability in the standard D1 format. Developed with a metal tube, stainless steel ball, and medium M grade, it provides crisp blue lines and smooth gliding on any paper weight. It fits perfectly with Kaweco Classic, Skyline, AL Sport ballpoint pens and other brands with universal D1 refills. The traditional blue shade is ideal for everyday note-taking, office environments, and school notebooks.