The Schmidt 888 refill is the most commonly used refill in rollerball pens. Odds are your rollerball pen will take a Schmidt 888 unless it is one of the following brands:

Schmidt 888 refills do not fit: Parker, Sheaffer, Waterman, Pelikan, Cross, Montblanc, Lamy.

The Schmidt 888 rollerball refill is a standard size refill made in Germany by Schmidt Technology. It will fit 98% of all rollerball pens which accept a standard European size refill. Fits most of these rollerball pens: ACME, Ancora, Aurora, Bexley, Bossert & Erhard, Caran d'Ache, Cartier, Colibri, Conklin, Conway Stewart, Curtis, Dani Trio, Delta, Ducati,Faber-Castell, Krone, Laban, Lalex, Lepine, Libelle, Mabie Todd, Marlen, Michel Perchin, Montegrappa, Monteverde, Nettuno, On line Pens, Omas, Porsche Design, Recife, Retro51, Romet, Rotring, Sensa, Signum, Stipula, Taccia, Think, Visconti, Waterford, Yard-O-Led and many more.