Run out of lead? Instead of throwing away your favorite pencil, replace the lead with these TUL refills. For use with TUL Mechanical Pencils. TO REPLACE REFILLS: 1. Pull off top cap that holds the eraser. 2. Add 3 to 5 leads of the correct diameter into the body of the pencil. Overfilling will cause the leads to jam. 3. Replace the top cap, 4. Click the lead advance button until the new lead starts to come out. Fits most 0.5 mm TUL mechanical pencils.