Description
The Amazon links below are representative. Clicking on them will also help you find other colors, line widths, and quantities.
The BIC Cristal refill will fit in most pens that take the B3 standard. The refill can always be cut down to fit pens other than the BIC Cristal, which is one of the most common pens on the market. This refill is available in black, blue, red, or green ink in a medium line width. Purchasing boxes of new Cristal pens is often no more expensive than buying a box of refills.
The Amazon links below are representative. Clicking on them will also help you find other colors, line widths, and quantities.