Schmidt 635 Refill for Lamy LM21 (M21BK) Ballpoint Pen (Black, 10-Pack) Schmidt 635M MINE Ballpoint Ink Refill 10-Pack Color: BLACK (also available in BLUE ~ GREEN & RED) Writing Nib: MEDIUM The refills measure: 2-11/16" (approximately) Fits the Lamy LM21 & some Swarovski pens (so check to make sure)