MVG23GN  Monteverde USA® Ceramic Rollerball (888), Green, Medium. Same as Schmidt 888. Fits most roller balls using standard style RB refills including Acme, Aurora, Bexley, Bossert & Erhard, Caran d'Ache, Colibri, Conklin, Conway Stewart, Delta, Monteverde, Pelikan, Retro 51, Rotring, Stipula, Yard-o-Led and others. Measures 110mm long (4.3 inches), 6mm dia (0.24 inches)