The LAMY M63 Rollerball Pen Refill is a rollerball pen refill that suits all LAMY Rollerball Pens with a cap. This means that it suits the Safari, AL-Star, Studio & 2000 Rollerball Pens. The writing capacity is 1500-2000m and it produces a beautifully thick, vivid line of 1mm width. It does not suit LAMY rollerballs that are cap-less such as Tipo and Swift rollerball pens. If you have a LAMY rollerball without a cap, you should purchase the M66 rollerball pen refill.