Pentel Premium Hi-Polymer® Lead refill has leads to offer smooth uniform writing and produce smooth/dark lines with reduce smearing. Each lead strand will last as long as a #2 wood pencil. For use with most refillable automatic pencils and Pentel mechanical pencils. Pencil Lead Format: Tube; Lead Diameter: 0.5 mm; Lead Degree (Hardness): HB; Lead Color: Black.